I updated to KDE SC 4.10.80 on Kubuntu Raring (13.04) today, after rebooting and logging in I was greeted by a black screen with only a cursor showing. After a bit of digging around I found that if I changed the compositor type from OpenGL2 to XRender and rebooted I could login like normal again. Afterwards trying to enable OpenGL2 again throws a message that OpenGL2 is not supported on this system. I think the fallback to XRender failed somewhere.
Reproducible: Didn't try
The system I'm using is a HP Compaq 6730s: http://www.hp.com/hpinfo/newsroom/press_kits/2008/connecting/ds_bn_6730s.pdf
It uses an Intel Integrated graphics chip.
Please attach the output of "qdbus org.kde.kwin /KWin supportInformation" and "glxinfo -l"
Created attachment 80718 [details]
Output of qdbus org.kde.kwin /KWin supportInformation
Created attachment 80719 [details]
Output of glxinfo -l
Disable color correction, it's what causes the black screen.
Nevertheless, on that chip the fixed function path (GL 1.3) or GLES (kwin_gles) will probably get you better performance on eg. blurring.
*** This bug has been marked as a duplicate of bug 321217 ***