No more synchronization - USB device not recognized

Hi,

I've been an Active Sync user for a long time, and always been satisfied
with its capabilities.

My problem is that a few days ago everything stopped working. All of a
sudden, every time I try to connect my HP iPaq rz 1720 to my laptop, I get a
message saying (in spanish, since my Windows XP SP 3 uses this locale) that
the USB device could not be recognized.

I tried every solution posted in every forum and web page: soft and hard
resets, reinstalling AS 4.5.0, buying a new connection cable, connecting to
the different USB ports available in my laptop... to no avail. It is now
completely impossible to get my PDA connected.

I have a smartphone and I can connect it without problems.

Any ideas?

Thanks alot!