VISTA will not SHARE certain file names?

My question is why will the file "mcafee_cq9765_en-us_3132007.exe"
fail to copy from an XP to a VISTA machine or the NETWORK. Yet if I
rename the file to "McAfee for VISTA.exe", and the transfer happens in
a blink.

This is the second time I have had to rename a file to transfer to the
VISTA machine.
The error is File in use but the transfer just hangs for 5 minutes
first..

Weird or what!!