Another thing which might be helpful in finding the bug might be this:

When i add radeon.agpmode=-1 to the kernel 2.6.32 commandline, the system shows
the same freeze behaviour as with 3.2 and 3.5, BUT it stays freezed only for a
few seconds, then continues to operate normally.

For that reason i am using radeon.modeset=0 (with kernel 2.6.32), which does
not lead to these short time freezes.

Please fix this serious regression. I dont want to buy new hardware.