Weird USB problem

I have a Gigabyte GA-8IPE1000 Pro motherboard with the F11 BIOS. Prior to
now, there have been no problems in the 14 or so months that I've owned this
motherboard. I can't say if it's the source of my problem, but maybe it is.

I have my mouse, keyboard and two game controllers hooked up into a powered
ADS Technologies USB 1.1 hub. The first time a problem happened to me was
earlier this week when my Logitech MX500 mouse suddenly stopped working
during a session of Windows. A few moments later, an error message appeared
near the bottom of the screen by the taskbar saying that a USB device has
failed and could not be re-initialized, or something to that effect. After
a reboot of Windows (using ALT-F4 and restarting), all was fine again.
Today, I noticed twice that my USB devices (keyboard and mouse) momentarily
failed. Shortly after each of these two momentary failures, I could hear
the distinctive Windows sound (through speakers) when new hardware is being
added. Shortly after this, the keyboard and mouse were working perfectly
again. I checked all of my connections after the first failure today, and
nothing was wrong. Everything was securely and tightly connected. I even
changed the power socket where I had the hub plugged in to.

What do you suppose could be causing this problem? For what it's worth, USB
2.0 is enabled in my BIOS and is showing up correctly under Windows XP. I
have Service Pack 2 for Windows XP installed and have had it installed for a
while now.

Thanks, I appreciate any feedback.