Problem with data stick and G4 iBook

I wonder if anyone can help about a problem I had today. I bought a new 8 gb HP data stick. I tested it on my G5 desktop and all seemed well. I went to library and spent about 6 hours downloading data for work. I could see all the files on the stick as I saved to it from the library's pc. I stopped the drive and ejected thumb drive from library pc when "safe to do so". When I got back to the office and inserted the data stick into my G4 iBook, the beachball appeared, the data stick flashed a couple of times and then everything hung. I had to restart the iBook and when I did it seemed to that it has reformatted the data stick erasing everything. At first I thought it must be a fauilty stick, but I tried copying to it again on the iBook and it handled over a gb of data without any problems. Any thoughts would be appreciated. Thanks.