I have been seeing complete lockups or black screens with every kernel since 188.8.131.52-96.
With the latest updates I get the desktop but it dies to black on the first attempt to click on anything.
I'm have an ATI R200 chipset(using Radeon) . I don't see anything unusual in any of the log files.
with the ...96 kernel, all is well.
I will likely try to reinstall with the RC if I don't find an answer soon.