External USB Harddisk ? Suse 9.2 freezes

Hi I?m using an external Harddisk (Western Digital External Storage 160 GB USB 2.0), formated with FAT, under Suse 9.2. The disk is recognized and mounted without problem. When I copy or delete a large amount of files to/from the external disk, the system freezes completly after 30 to 60 seconds (not constant). Copying/deleting individual files is not a problem. The external disk works perfectly under windows XP. Is anybody using the same disk without problem? Any Ideas? Thank you - Christopher