CUDA invalid device symbol error on cudaMemcpyToSymbol


In your CUDA code, you have a cudaMemcpyToSymbol call of this form:

cudaMemcpyToSymbol( "deviceVar", hostVar, hostVarSize, 0, cudaMemcpyHostToDevice );

This gives a runtime error of invalid device symbol.


Check if you are using CUDA 5.0 or later. The technique of passing the device symbol by using its name string is gone in CUDA 5.0. Instead, just remove the double quotes to specify the device variable itself like this:

cudaMemcpyToSymbol( deviceVar, &hostVar, hostVarSize, 0, cudaMemcpyHostToDevice );

Tried with: CUDA 5.0


Mercurial: Not trusting file from untrusted user or group

Mercurial gives this error for the hgrc (Mercurial configuration file) when the user running a Mercurial command is not the same as the owner of hgrc. This typically happens on servers, shares or distributed filesystems.

To fix this, add a trusted section to the configuration file to tell Mercurial to trust the user or group reported in the error.

For example, if Mercurial complains that it does not trust joe and you happen to trust him, add him to hgrc:

users = joe

Tried with: Mercurial 2.0.2 and Ubuntu 12.04.1 LTS

Reboot loop after XBMC nightly install on Raspbmc

After installing a XBMC nightly on Raspbmc and choosing to restart the system, it went into a loop. XBMC would repeat “Relax XBMC is restarting” endlessly.

Of the many solutions offered online, this worked for me.

  1. SSH into Raspbmc as user pi. Only XBMC is stuck in a loop, so this means that the underlying Raspbmc Linux OS is still running and accessible. This is the reason you can SSH to it.
  2. rm ~/.xbmc-current
  3. Reboot the system.

Tried with: Raspbmc RC5 and XBMC rbp-20121231

PDFTK: Owner password required error


You try to manipulate some PDF files using PDFTK and it gives the following error:

Error: Failed to open PDF file:
   OWNER PASSWORD REQUIRED, but not given (or incorrect)


The PDF files for which PDFTK prints this error might be password protected or encrypted. If you can open and view the PDF file using any PDF viewer then it might mean that the PDF files are protected or encrypted with an empty password.

To be able to apply PDFTK on these files, you will need to remove the protection or decrypt the files. One way to do this is using the QPDF tool.

Tried with: PDFTK 1.44

VT-x is not available for VirtualBox

VirtualBox error


A virtual machine running Ubuntu in VirtualBox which was working fine threw up an error when I tried to restore it. The error read:

Failed to open a session for the virtual machine Ubuntu-12.04-LTS-x64.

VT-x is not available. (VERR_VMX_NO_VMX).

Result Code: E_FAIL (0x80004005)
Component: Console
Interface: IConsole {db7ab4ca-2a3f-4183-9243-c1208da92392}

This happened even though I had not changed any settings in VirtualBox.


VT-x is hardware visualization which the Intel Core i3 M330 processor I have does support. It was strange that the hardware visualization feature suddenly was not available to VirtualBox.

Then I remembered that I had enabled Hyper-V earlier in the day. Windows 8 ships with Hyper-V and I had turned it on to try it out. It turns out that Hyper-V grabs hardware visualization and VirtualBox is left stranded not being able to access it.

I disabled Hyper-V and my VM in VirtualBox booted up without any errors.

Tried with: VirtualBox 4.2.4 and Windows 8 Pro

The strange case of the incorrect side-by-side configuration

Side-by-side configuration error

A week ago VirtualBox informed that a new version was available and that I should update to it. I proceeded to get the latest version using Chrome, which downloaded as the file VirtualBox-4.2.4-81684-Win.exe. On executing the file, I got this error:

The application has failed to start because its side-by-side configuration is incorrect. Please see the application event log or use the command-line sxstrace.exe tool for more detail.

This error was a bit troubling to me because I have not seen any DLL or SxS problems with Windows 7 and recent versions of software. Those happen mostly with older versions of Windows and older software.

Searching online for this error leads to suggestions that one should install a particular version of the Visual C++ Redistributable package. None of those solved the problem however.

I finally suspected the file itself. File downloads rarely get corrupted these days, but it can still happen. So, I downloaded the file again and it installed without any complaint! 🙂

Just to confirm I opened up the two files in WinMerge and found that there were a few bytes at the end of the second file missing from the first downloaded file.

Tried with: VirtualBox 4.2.4 and Windows 7 Enterprise

Visual Studio 2010: Conversion to COFF failure

Conversion to COFF failure.


I installed Visual Studio 2012. After that when I tried to open an older C++ project in Visual Studio 2010 and compile it, I get this error:

LINK: fatal error LNK1123: failure during conversion to COFF: file invalid or corrupt


This is an error caused by the installation of Visual Studio 2012. To fix this, just download and install the Visual Studio 2010 Service Pack 1. The SP1 install takes a while. The error should be gone after that.

Tried with: Visual Studio 2010, Visual Studio 2012 and Windows 7 x64

Component MSCOMCTL.OCX not correctly registered

MSCOMCTL.OCX error dialog


After I installed MP3Gain on Windows 8 and executed it, it threw this error:

Component ‘MSCOMCTL.OCX’ or one of its dependencies not correctly registered: a file is missing or invalid


This error is caused because either the file MSCOMCTL.OCX is missing or it is not registered with the registry. To fix it, try the following:

  1. Find a copy of this file. You might find this file somewhere among your Windows application directories or can be found online. Place the file in a directory which will not be tampered with.
  2. Open a command prompt with Administrator privileges.
  3. Register the file by using the regsvr32 command: regsvr32 C:\path\to\MSCOMCTL.OCX

After the registration is successful, run the application again and it should execute without throwing this error.

Tried with: Windows 8 x64 and MP3Gain 1.2.5

LibreOffice installation error


LibreOffice install error message

I tried to install a new version of LibreOffice (v3.6) over an existing old version (v3.3). During the install process, it threw up this error dialog:

Please exit LibreOffice 3.3 and the LibreOffice 3.3 Quickstarter before you continue. If you are using a multi-user system, also make sure that no other user has LibreOffice 3.3 open.

I checked and LibreOffice or its Quickstarter were not running. Nor was any other user on my computer logged on.


Not being able to find out why the installer was giving this error, I gave up. I uninstalled the older version of LibreOffice and tried the newer version installation again. It worked fine this time.

Tried with: LibreOffice 3.6

Fixing noisy HDMI audio output


I connected a Dell Inspiron 1320 notebook with HDMI output to a Toshiba REGZA LCD TV using a HDMI cable. The notebook is running Windows 7 Home Premium. When I play a video file on the notebook, both the audio and video from the TV seems to be fine. However, when you actually sit down to watch for a longer time you notice that the audio sounds kind of muffled or noisy and the spoken words are hard to distinguish.


First, I suspected the TV, since it has so many audio settings in its menus. After testing all possible audio combinations on the TV, there was no improvement in the audio.

Then, I decided to turn to the Dell Inspiron 1320. The HDMI video and audio from this notebook is generated by its Intel GM 45 chipset. I used the Support section of the Intel webpage to check if any of the notebook’s Intel hardware had newer drivers. And yes, there was a much newer graphics driver available. I downloaded, installed it and rebooted the notebook. When I connected the TV, the new driver could now detect that it was a Toshiba TV that was connected through HDMI and needless to say that the audio output was perfect! 🙂

Tried with: Dell Inspiron 1320 and Toshiba REGZA LCD TV