WordPress MU

I am having a terrible time trying to upgrade from 2.6 to 2.7 using the instructions, deactivating plugins, with no errors in my log files.

My version file says I have 2.6, and I know there is also a 2.6.5. Should I upgrade to 2.6.5 first? And, if so, what are the proper instructions for doing so?

Thanks in advance!

2.6 to 2.7 should be fine. You have to figure out why you have the white screen. Is it just on the front end? Can you log in to the backend? Does switching the main blog theme to the default (via the database) get rid of it?