USB2 Flash Drive problem

Hi guys -
Got a nice 2gb usb flash drive - but on certain machines I get a delayed write failed - I was thinking it was only Windows 2000 boxes with only USB 1.1. support, but had it on 3 pc's at ITN, but don't have the problem on either of my workstations.
The issue is, it did it on a server I was collecting a logfile from (even though it was a purely monitoring machine, they still panic'd a bit!)

Chkdsk doesn't throw any errors - can anyone think of a specific USB test util that might be able to shed some light. HDDtach shows a flat 9.6MB/s transfer rate which is expected with no blips.

Any ideas?

Cheers,

Scott