USB 2.0-Windows 2003 Server

I have been trying to use an external USB 2.0 hard drive to back up my 400SC. Whether I try file copy or Backup Exec, I can copy aboout 2 gigabytes, and then the server goes into la-la land with an error during a paging operation or delayed write failure or a "system failed to flush data to the transaction log". I think this is a bug with the 2003 server USB driver. Any comments?