While trying to get tech support for a problem with my backup software, I was asked to submit a System Information (.NFO) file. When I did, the support person wrote back saying it was corrupt.

Well, it turns out if you try to open a .NFO file by double-clicking it in Windows Explorer, you do indeed see the message:

System Information cannot open this NFO file. It might be corrupted or an unrecognized version.

This is most likely a bug in the System Information program (msinfo32.exe). The work-around is to start System Information file (Start > All Programs > Accessories > System Tools > System Information) and then do a File > Open to open the file. This works without any problem.