Microsoft Wireless Intellimouse Explorer

I'd like to help get my Microsoft Wireless Intellimouse Explorer
working under 5.3-RELEASE.  I've installed 5.3-RELEASE (x86) and 
updated to about 3 AM PST with the GENERIC kernel, and the mouse
is recognized as ums0:

ums0: Microsoft Microsoft Wireless Intellimouse Explorer\M-. 1.0A, rev 1.10/0.0e, addr 2, iclass 3/1
ums0: 5 buttons and Z dir.

So the driver sees it, but I can't get much output from the mouse.
moused starts and sees the device, but I'm unable to move the cursor
in X or on the console.  If I kill off moused and point X at 
/dev/ums0, X can't open the device and I get the message:

usbd_setup_pipe: failed to start endpoint, TIMEOUT

I've also tried ' moused -p /dev/ums0 -i all ' after killing off
moused and I get:

moused: unable to open /dev/ums0: Input/output error

I've got about two weeks to poke and prod and I'd like to work
with someone to get this mouse working.  I'd rather not have to have a
separate mouse for FreeBSD than for Windows XP.  (And as an odd side
note: it works in Solaris 10 (x86), though Solaris won't install
properly on this machine.)

Any help would be appreciated.  I can provide remote access if needed.

-- 
Chris Johnson
cjohnson_at_wcug.wwu.edu
Tua toga suspina est.