What can go wrong with simple copying?

I have two windows 2000 Advanced servers side by side. One is a DC and the other a member of the same domain. Exact same hardware, OS level, patches, etc. On one of them I have some files that I need to copy to the other. So I mapped a drive and simply started copying. It copied some files, then gave me an error ” Can not copy file Setup.BMP Invalid MS-DOS function. Curious! I tried to copy the directory to another partition, same error. Tried to copy to the same partition, same thing. Tried from CMD line, same thing! Looked at the attributes and properties, nothing unusual, not compressed, encrypted, or read-only. Tried other directories, some files gave me the same thing! The only common thing seems to be that all these files are from DOS or Win98 systems!

So, can anyone help me with this?

Thanks

Fred