Suite Upgrade to 4.2PL2 hangup
 

I'm trying to upgrade ti the latest version from 4.1.11. The upgrade script never really kicks off. It starts out looking right, with this: "Status: Processing 4.1.12 Alpha 1, Step 1 of 2", but it never gets anywhere. The details box is empty, and the progress bar is all white.
I tried a few times last night, I let it run for over a hour one time. Today, I've re-downloaded and re-uploaded all files (the no image pack), and it has been standing still for a good 20 min now. What do I do?