I have seen already this thread about a similar problem, but it didn't resolve mine.
When I try to change some settings on desktop effects, I always get a message of this kind:
Kwin Window Manager
The following desktop effects could not be activated:
- Blur
- Cover switch
- Desktop Cube
etc.

Code:
wrbbt:~ # uname -r
2.6.34.10-0.2-default
wrbbt:~ # cat /etc/SuSE-release 
openSUSE 11.3 (i586)
VERSION = 11.3
wrbbt:~ # lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller (rev 0c)
Any ideas? I more info is needed, please, ask.
Thanks in advance.