I clicked the Enable Desktop Effects in KDE 4.3.5 on OpenSUSE 11.2, and my screen froze up. I POR'd to reboot, and after logging in with KDM, it froze again, consistently, when the progress bar (under the SUSE logo) is about halfway across. There's a long "blink" of the splash screen (after which the mouse moves VERY slow), and it never progresses beyond the spash screen.

I tried KDE Failsafe in the session options, but it also behaves identically. I would think that Failsafe would not enable desktop effects.

I say "terrifying" because I couldn't figure out how I was going to disable the desktop effects since I couldn't log into KDE. I count my lucky stars that I had put the Personal Settings icon onto my desktop. I was able to log into Gnome and unclick the desktop effects from there.

I was resolved to not using desktop effects, when I found this thread about ATI cards and desktop effects: viewtopic.php?f=111&t=84432. Near the end is a suggestion to use XReader intstead of OpenGL, and this worked for me. So now I have some effects, though many of them come back with XRender telling me that they can't be enabled.

So why couldn't I get around the freeze with Failsafe, and how else could I have unchecked the desktop effects?

Also, any ideas as to why OpenGL freezes KDE?

As far as my card is concerned, it's a ATI Radeon HD 4800. I'm running the radeon, but also tried radeonhd to get around the problem which it didn't.

The freezing of your system is likely related to a bug in your graphics drivers. Please make sure you have the latest versions installed from the ATi website ( distribution package managers tend to be out of date in this regard, and may not contain essential fixes for stability and performance )

Why fail safe mode failed I do not know. KWin should disable its Desktop Effects in that case. I would recommend filing a bug at the openSUSE bugzilla as their scripts that launch fail safe mode may contain a bug which means the fail safe launch ends up as a normal launch.