Windows 7 SP1 failure configuring service pack

Got a problem guys. I have a workstation where the SP1 install didn't go well at all. It's Windows 7 64 bit. The drive is encrypted with McAfee Endpoint Encryption.

What is happening is that it boots to a Windows screen that says, "Failure configuring Service Pack. Reverting Changes. Do not turn off your computer."

Now I have seen this before, and it usually just rolls off the attempted update. However, yesterday it would just stay on this screen for over an hour to two hours. I would continuously see HD activity on the HD activity light, but that's about it. I tried some fixes from the net like deleting the pending.xml file from the winsxs folder, but that didn't help. I finally gave up and let the thing just run all night.

When I came in this morning, it appeared to have rebooted itself, because it was back on the preboot screen for McAfee. I started the computer again, and again it's back to the same message, but the HD activity light is still moving, so I assume it's trying to do something?

Question is, if you have seen this behavior, how many times does it automatically reboot when reverting a service pack off a HD? If this is a loop, how do I break out of it? Many thanks guys!