[CentOS] CentOS4 desktop has stopped recognizing removable media - haldaemon problem?

USB sticks and cameras used to pop right up on my desktop.  Now they
don't.  I've checked the Gnome "Drives and Media Preferences" and
nothing has changed -- I have "Mount removable media when inserted"
etc.  (Tried toggling it off and back on, no effect.)

I've logged out and back in, even rebooted.  /var/log/messages shows
the devices are being recognized by udev:

Jun 27 19:53:37 torch kernel: Attached scsi removable disk sde at
scsi11, channel 0, id 0, lun 0
Jun 27 19:53:37 torch scsi.agent[13576]: disk at
/devices/pci0000:00/0000:00:0b.1/usb1/1-5/1-5:1.0/host11/target11:0:0/11:0:0:0
Jun 27 19:53:37 torch udevd[1347]: udev done!
Jun 27 19:53:47 torch udevd[1347]: udev done!

However, that's followed by this:

Jun 27 19:54:07 torch hald[5179]: Timed out waiting for hotplug event
699. Rebasing to 699

I restarted hald (service haldaemon restart) and it picked up one of
the two devices I'd plugged in, but not the other.