Sounds like you have the wrong user name and password in your XM Radio Online settings in the software. The settings are filled in on the configuration window (right side - middle).
Those are correct and are the original settings for the software. You're failing the logon which would mean that something you put in the two spaces above that (your online account information) is wrong.
Try going to the XMRadio Online website and logging in. If you can get in there but not in TT, then you have something wrong with TT which may require some fixing.
XMRadio Online website works fine. In fact, because TT has been down (for 2 months), I bought Total Recorder, and have successfilly recorded from XM. TT has the problem. I just bought Total Recorder yesterday, so that is not the cause.