ML310G5 External USB disk issue

[Fossola]

Hi,
i'm trying to use external USB disk (WD, Dell & no name).
The first time i attach the USB disk all run fine and i can see the external disk content and/or write on it.
When i remove the ext. disk following the correct procedure, all is ok and the disk disappear from explorer.
Now, if i reconnect the disk, nothing happen,i can't see it, i can't remove it and a process (rundll32) start and hang, i can't kill it, and i can't shutdown the server.
OS is Win 2003 server R2 fully patched like the hardware drivers.
Many thanks for some help.