usb network device stops working at random times

I'm having severe problems with the at76c503 driver - the network device
works, but every once in a while, at seemingly arbitrary times, it'll stop
working, and this is often accompanied by the keyboard locking up. Even
when the keyboard doesn't lock up, I have to reboot because ifconfig will
freeze (the entire system) anytime I run it after that.

The way I have it set up is, after each boot I connect the USB device, su
to root, and run the following commands:

iwconfig wlan0 mode managed essid any channel 6
iwconfig wlan0 ap 00:04:5a:db:a3:37
iwconfig wlan0 key [1] restricted 72A0DEB3ABAA6FA02D398D7279
iwconfig wlan0 key on

ifconfig wlan0 192.168.1.101

echo I used to do "ifconfig wlan0 promisc" here, but no longer; it doesn't
seem to make a difference though.

route add -v default gw 192.168.1.1

The reason I don't have the device in while booting is that, if I do that,
while it's in the process of "checking for new hardware" it prints a bunch
of garbage and something about the kernel having an unhandled exception.

I'm using Fedora Core 2 with kernel 2.6.5-1358, the driver is at76c503
v0.12beta11. The device is a Linksys wireless USB access point, the newer
version (2.6 I think). When the network goes down and keyboard locks,
/var/log/messages shows something resembling this:

May 31 20:30:10 localhost kernel: uhci_hcd 0000:00:10.1: host system
error, PCI problems?
May 31 20:30:10 localhost kernel: uhci_hcd 0000:00:10.1: host system
error, PCI problems?
May 31 20:30:10 localhost kernel: uhci_hcd 0000:00:10.1: host controller
halted, very bad!
May 31 20:30:10 localhost kernel: uhci_hcd 0000:00:10.1: host controller
halted, very bad!
May 31 20:30:20 localhost kernel:
/usr/src/redhat/BUILD/at76c503a/at76c503.c: wlan0: lost beacon bssid
00:04:5a:db:a3:37
May 31 20:30:20 localhost kernel:
/usr/src/redhat/BUILD/at76c503a/at76c503.c: wlan0: lost beacon bssid
00:04:5a:db:a3:37
May 31 20:30:21 localhost kernel: usb 3-1: control timeout on ep0out
May 31 20:30:21 localhost kernel: usb 3-1: control timeout on ep0out

When the keyboard doesn't lock, it doesn't show the "uhci_hcd" lines. It
seems however that on times the keyboard does lock it doesn't do so until
the time the "usb 3-1: control timeout" line shows up. When the keyboard
does not lock it shows lines like this, after the lost beacon and control
timeout:

Jun  1 00:32:36 localhost kernel:
/usr/src/redhat/BUILD/at76c503a/at76c503.c: wlan0: start_scan failed with
-110
Jun  1 00:32:36 localhost kernel:
/usr/src/redhat/BUILD/at76c503a/at76c503.c: wlan0: start_scan failed with
-110

A quick scan of /var/log/messages shows that the start_scan message never
seems to come up the times that the keyboard locks. Like I said, the
occurrences are mostly random. However, on a few occasions I've noticed
they happen at about the same time I do something requiring lots of CPU
for an extended time, such as starting Mozilla, or encoding an ogg file.
This has happened with both the keyboard-locking and non-keyboard-locking
varieties, and I should point out, the majority of the times this happens,
nothing out of the ordinary is going on at all (it's happened when I
wasn't even there at the computer).

Please let me know if there's more information I should provide.
Assistance would be greatly appreciated, since this is the only thing
preventing me from having a happy life at the moment. Thanks!

-graue