KWin crashes

KWin version: 4.8.4-2.3.1
Every time the computer boots and I log in, I get a message from KCrash that KWin crashed. I click on OK and everything seems to be working fine (all desktop effects are working). If I log out and log in, I get the same message and behavior. If I run

kwin --replace

in the ‘Alt-F2’ textbox, all goes well, and if I log out and log in again, there is no crash message about KWin.
Also note

billy@desk-SuSE:~> kwin --replace
QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave.
OpenGL vendor string:                   ATI Technologies Inc.
OpenGL renderer string:                 ATI Radeon HD 5800 Series 
OpenGL version string:                  1.4 (2.1 (4.2.11762 Compatibility Profile Context))
Driver:                                 Catalyst
Driver version:                         2.1
GPU class:                              EVERGREEN
OpenGL version:                         1.4
X server version:                       1.12.3
Linux kernel version:                   3.4.6
Direct rendering:                       no
Requires strict binding:                yes
GLSL shaders:                           no
Texture NPOT support:                   yes
kwin(19123): glCheckFramebufferStatus failed:  "GL_NO_ERROR" 
kwin(19123): Failed to compile fragment program:  
kwin(19123): Shaders are not supported 
kwin(19123): Shaders are not supported 
kwin(19123) KWin::checkGLError: GL error ( PostPaint ):  "GL_INVALID_ENUM" 

Any idea why KWin crashes ? I see the ‘Shaders are not supported’ message, but I don’t know what to do about it. I have the proprietary drivers, version 12.8.
Thank you in advance

No clues anyone ?
I have also experienced this following behavior too. I log in and the effects sometimes do not work and Configure Desktop > Enable Desktop Effects > Enable desktop effects at startup is disabled (it normally should be enabled). If I enable this option and click apply, I get a message saying ‘The following effects could not be enabled’ and it lists all the effects I use. However, on the next boot, effects work. I don’t know what causes the option to become disabled.

What seems more important to me is this one:

Direct rendering:                       no

no error messages during install of the Catalist driver?

I’m 99% sure there weren’t any. Should I try uninstalling them and installing them again ?
I have no idea how to uninstall them though, never had to do that…