After using a USB flash drive or memory card on my laptop (Win XP SP2) I get the following dialog saying:
There is no disk in the drive. Please insert a disk into drive .
Notice the space between the last letter and full stop. That has to be a placeholder probably for something like a drive letter but it's empty.

This will never leave. Whenever I press anything on this dialog, it will come up after a couple of seconds so I just drag it outside of the screen. It will only go away if I reboot. A serious problem is that the existence of this dialog blocks the startup of some programs, for example mspaint.
I've tried rearranging the drive letters for removable media via Disk Management but no luck.
This has been happening for the last six months.
Any ideas?