USB Detect Failure!

[L. V. Lammert]

Trying to get a pair of 80GB USB drives setup for a rotating backup, .. 
drive *A* detects and works fine; drive *B* refuses to detect! Whenever I 
unplug *A (removal detected properly) and then plug in *B*, no attach is 
detected, and the system will no longer detect **ANY** USB drives. 
Rebooting the server will allow detect of *A*, but never *B*.

Took drive *B* back to the shop, and tried it in a local machine (with 
bsd.rd - below) - WORKS FINE!! Is there ANY logical reason why this drive 
would not detect in System 1, but work just fine with System 2?? Can't get 
to the dmesg of the server right now, but it's an ASUS A7V880 MB.

Any suggestions would be greatly appreciated!
===========================
USB 80GB Drive "B" on test system:
Attach 1:
umass0 at uhub0 port 1 configuration 1 interface 0
umass0: Cypress Semiconductor USB2.0 Storage Device, rev 2.00/0.01, addr 2
umass0: using SCSI over Bulk-Only
scsibus2 at umass0: 2 targets
sd2 at scsibus2 targ 1 lun 0: <ST380011, A, 0 0> SCSI0 0/direct fixed
sd2: 76319MB, 76319 cyl, 64 head, 32 sec, 512 bytes/sec, 156301488 sec total
Detach 1:
umass0: at uhub0 port 1 (addr 2) disconnected
sd2 detached
scsibus2 detached
umass0 detached
Attach 2:
umass0 at uhub0 port 2 configuration 1 interface 0
umass0: Cypress Semiconductor USB2.0 Storage Device, rev 2.00/0.01, addr 2
umass0: using SCSI over Bulk-Only
scsibus2 at umass0: 2 targets
sd2 at scsibus2 targ 1 lun 0: <ST380011, A, 0 0> SCSI0 0/direct fixed
sd2: 76319MB, 76319 cyl, 64 head, 32 sec, 512 bytes/sec, 156301488 sec total
Detach 2:
umass0: at uhub0 port 2 (addr 2) disconnected
sd2 detached
scsibus2 detached
umass0 detached