I experience the problem e.g. described here: http://fedoraforum.org/forum/showthread.php?t=103776 Attaching the device, browsing and starting to copy files to/from it works fine. But during copy after a short while the copying gets stuck and all of a sudden syslog shows kernel: usb 2-1: reset high speed USB device using ehci_hcd and address 3 then the stall is gone for another minute or so. Unloading ehci_usb manually (actually dropping down to USB 1.1) works, but sure is slow.
Can you try a 2.6.25.10 based kernel when it becomes available?
Had the chance to lately check the problematic device again with kernel 2.6.25.11-97.fc9.x86_64. Seems to work fine now.