I have an 8 GB. I have an 8 GB PNY Attache flash drive that can be read by a Windows XP operating

Question

I have an 8 GB PNY Attache flash drive that can be read by a Windows XP operating system but not on a Mac OS X operating system. The problem is even more confusing because a Mac that can run both Windows and the OS X can read the flash drive when started up in a Windows environment but not when started in a Mac environment (same port used for the flash drive in both instances). Any thoughts as to why...