I often get a decompression CTD, and it's always some textural file. Verifying files doesn't help but restarting the computer always fixes it, so I guess it is some kind of error in temporary memory. How do I reset this without restarting my computer?
How much RAM do you have? If you don't have enough, that might be the problem. (I have no problems with just 4 GB, and they recommend 2 GB or more. So I kind of doubt this is the problem, unless your computer is really old.)
Alternately, you might have a RAM stick that's starting to go bad, and whenever it hits that bad spot, it crashes. But it seems to me that if that were the case, it would happen with other memory-intensive software as well.
Alternately, since it crashes while decompressing texture files... the CTD might not be with decompressing the textures, but with transferring them to your video card. Which means I also need to know what kind of video card you have, as well.
In fact, now that I think about it, most onboard video shares your RAM with Windows. So it's still possible you may not have enough RAM, if an onboard video chip is taking too much of it. (Usually they claim between 128 MB and 512 MB.)
Anyway, how much RAM do you have and what kind of video card are you using? I'll try to help you figure your problem out.