> > reported errors, or a header crc32 mismatch was found.' What does that mean?
>
> It means your zipfile is most likely corrupt. cmpro decompresses the archive to
> memory, recalculates the crc32 values and compares it against the one in the
> datfile *AND* against the data found in archive header.
>
> There are NO reliable sources. Bad zips are a common thing.
>
> If you got the problem that one and the same archive produces such a problem
> randomly (i.e. one scan it's fine, the other scan it's bad, then fine...then
> bad..). Then your system may have a problem. This can be either a different
> program interfearing (e.g. Virusscanners) or RAM/HD is bad.
>
> What you can do is: simply mail me such a zip and I'll have a look (if mail
> doesn't work, put it somewhere where I can grab it).
> ..or simply open the archive in question with a common zip program
> (winzip/winrar/7zip/etc..) and run a test operation.
>
>
> Roman Scherzer
>

Thanks for the advice Roman... I have a feeling the problem does indeed relate to my system - I forgot I had realtime virus scanning going on at the same time. I am also going to do a scan for errors on my external drive which the roms are on. I'll try the test operation with winzip as well.