Volume Query Failed.
WMI Query Failed. Provider failure.
I eventually tracked it down to an issue with TrueCrypt 7.1a. It seems that when TrueCrypt unmounts a drive, it can sometimes leave behind a "ghost" volume, that is invalid and causes the manager to throw the error. You can test if this is the cause on your machine by typing "mountvol.exe" and looking for any errors like "The system cannot find the file specified". This bug/issue was mentioned on the TrueCrypt forums back in 2008, so it's not new.
The only solution I've come up with is to make a tiny TrueCrypt container, and leave it mounted on that drive.
Edit: Included link to Truecrypt forums post about issue.