Originally Posted by Chevalr1c
Maybe it is as simple as some RAM issue related to some wonky BIOS setting? I could be wrong about that though.
When (de)compressing files a slight instabillity can be enough to corrupt the archive, although some archive types are more sensitive to this than others (LZO for example is very sensitive, I do not know whether this is also the case with 7-zip).
Maybe it's the version of 7-ZIP? I don't think this will really help but it's worth giving a try. I really think it's the file though. Does it throw the CRC error at the same point every time you try decompressing it? If it does, it's data corruption for sure. If it's random, it could be memory but I would imagine that a lot of other things would be going haywire at that point. I don't think 7-ZIP is as touchy as LZO.