Hi All -
I found a rather simple solution to this problem, so YMMV but it worked great for me! If you are having troubles logging into the admin after upgrading to Magento 1.2.1, then this is a very simple check/fix.
Initially the fix that worked and ended my 6 hours of hell last saturday, entailed commenting out 3 lines of code in:
Today, it dawned on me that the admin section addresses this specifically, of which my values were blank!
1. System > Configuration
2. Session Cookie Management
3. Fill in Cookie Domain with your domain
4. Fill in Cookie Path with just a ‘/’ (no single quotes)
5. Save, Log out, Log in.
So this is what I found that works, so Varian didn’t mess anything up really, they just got more code working the way it should have!