USB devices no longer detected, why?

Config:
MicronPC Millennia AMD Athlon upg to 2.13ghz
GA-7DX Rev 2.2
BIOS F2C
Windows XP SP2

Problem:
Here is the chain events that led to the problem. First, I have 2
different USB SAN disks and system always detected them when conn to front
of the tower. I also had a USB Logitech web-camera and a USB Epson CX4600
all working fine.

The CX4600 had a known problem with the ink-cartridges, sw said it was low
or empty where it still have enough ink remaining. I received a new
CX4800. I then uninstalled all Epson sw, rebooted, and connected the
CX4800. Inserted the new Epson CD sw that contained drivers & sw, but it
did not detect the CX4800. Tried de/re-attaching the USB cable at the
printer end, system did not detect any new devices. I also tried to conn
the USB printer to 2 other different USB ports, same problem.

I then tried to attach my SAN disks, still system did not detect any new
devices. I detached all USB devices and only tried the SAN Disks, still
problem. It seems Plug n Play does not work or got disabled.

I checked Device Manager and it shows the following with no red/yellow:
Universal Serial Bus Controllers
- USB Root Hub
- USB Root Hub
- VIA Rev 5 or later USB Universal Host Controller
- VIA Rev 5 or later USB Universal Host Controller

I then removed all 4 items above by clicking on it and choosing Uninstall.
I reboot, it detects them but does not detect the SAN disk still
attached. I tried the web-camera device alone, same problem.

What is happening, any suggestions?? THANKS!

p.s. I attached the the SAN disks, Epson printer and webcamera to a
Gateway 500mhz system running Win2000 and it detects them.