This appears to have done the trick. Thanks for all the good information! I am continuing to receive errors with some virtual machines but not all. The error codes are:

2008-08-04 17:27:15.542 'vcbMounter' 3772 error Error: Error while opening disk vpxa-nfc://<vm info>:902!52 b0 51 2d de 0b d9 40-f9 0c 65 c7 6c 2c 6f 23: A virtual disk could not be opened. -- An invalid field name was used in a query string (Exception from HRESULT: 0x80040204)

and the ever-entertaining

Unknown error:
Exit Code: -2146234327

I'm going to create a separate thread for these errors, though.

Thanks again,

Tom