FYI... revised: https://bugzilla.redhat.com/show_bug.cgi?id=472634 after KDE 4.2 push yesterday. Previously with 4.1 Desktop effects enabled appeared to work fine with nomodeset, but after 4.2 things went south in a big way. Didn't matter if I used modeset or nomodeset, X would loop. Most times I could SSH in and reboot the system, but sometimes system completely locked up. Initially I had opened against Radeon 200M, but now my desktop system is affected (Radeon X300). Another report was with a Radeon X550 - so this seems pretty pervasive with the Radeon chipset. Not sure what changed in 4.2 with desktop effects, but whatever was uncovered, triggered badness. At this point it looks like KDE4.2 + Desktop Effects + Radeon = Xorg Loop
