Hallo,

after testing aticonfig more and reinstalling of the fglrx driver version 1:8.12.4 and rebooting now the stripes around the cursor appears every time, not only by two monitors.
After reboot stripes over the whole monitor apperas, which occurs before only, if 2 monitors were connected. Checking the folder etc/X11 shows, that there were two new files created: xorg.conf.fglrx.0 and xorg.conf.original, which does not were there before. After deleting this 2 files, change in xorg.conf the driver to radeonhd, and reboot i have now every time only the stripes around the mouse cursor.

So I think the problem is related to some problems or wrong setting of xorg and/ or the used ati-grafic card. But i does not know how to get deeper in it and solve it.

A newer version of the flgrx-driver i could not install, since for this my xserver-xorg version is too old.

Stefan