Using Toad 10.5, it's not possible to login to PVCS Serena ChangeManager v8.1.0. The OK button on the login screen is greyed out - if there is a password entered, or if it is left empty.
Using Toad 10.1, this works ok.
WORKAROUND:
None.
This is addressed in the v10.6 beta version, available from: http://toadfororacle.com/beta.jspa