Why are ALL of my .dat files now .vcd files?

[LOLZpersonok]

I found this out when I went to play GTA IV. I noticed that all of the water was missing. So, I went and looked in the installation folder and found that all of my once .dat files are now .vcd. How did this happen, and how can I fix this problem? The same applies for ALL of my installed games. It wasn't like this before.

What on earth happened?! I need help now!

 

[Kage]

Ah ha, looks like from research, that it is something to do with a program (for example Nero) changing what opens the files.

You can counteract this.

Go to Windows Explorer (windows button + E as a shortcut)Tools\Folder Options\File Types and scroll to .DAT and select Restore to Default.
Or find the associated program and delete it from the list.

Also this apparently does the trick:

Click Start, Run and type this:

reg delete HKCR\.DAT /ve /f

 

[LOLZpersonok]

Ah ha, looks like from research, that it is something to do with a program (for example Nero) changing what opens the files.

You can counteract this.

Go to Windows Explorer (windows button + E as a shortcut)Tools\Folder Options\File Types and scroll to .DAT and select Restore to Default.
Or find the associated program and delete it from the list.

Also this apparently does the trick:

Click Start, Run and type this:

reg delete HKCR\.DAT /ve /f

Thanks. The first thing you explained helped. The .DAT file extension was not origionally there, so I just added it there and now everything is fine. Thanks Again!