Someone in our local MUG pointed out that every time you copy a file to a Zip disk in 10.1.5, the date changes. She tried to reformat the disk using Iomega Tools, but it did not solve the problem. She talked to Apple and Iomega Tech support and no one she talked to had heard of this. I tested it and sure enough, the modified date is set back one hour every time you copy a file to the disk.
After doing some testing, I figured out that if you reformat the disc with Apple's OS X Disk Utility (the one they bundled with the OS), the problem is solved.

