It seems that after being up for a few days, my Ubuntu system refuses to auto-mount hot-plugged USB disks (i.e. flash drives). The output from dmesg shows that the kernel recognizes the device correctly. The only solution I'm aware of at the moment is to reboot (logging out may work as well, but the impact is the same since I have a bunch of stuff open and it takes a few minutes to get everything situated after startup/login).
I thought gvfs-fuse-daemon was the thing responsible for managing filesystems in userspace, but killing and restarting that doesn't help. Any other ideas?
(Ubuntu 9.10, gnome, 64-bit)