xrandr issue in KNOPPIX_V7.0.5CD-2012-12-21-EN

I love Knoppix 7.0.5.

There is one annoying issue when operating dual monitors on my PC - an ACER Aspire AX1800 Quad Core with ATI Radeon HD4650 1024mg RAM video graphics. Monitor 1 HP 2309m HDMI connection, Monitor 2 Benq GL2440 DVI connection.

The problem is, when I move a window from monitor 1 to monitor 2, as the window moves into monitor 2 it leaves trails (like mouse trails) behind it. This makes it hard to see what I'm doing as every time I move a window I get dozens of overlapping windows in a trail. Is anyone else experiencing this with Knoppix and xrandr?


I use the same dual monitors in Win 7, and they have tested okay on Ubuntu and Fedora current versions. Not sure why this issue happens in Knoppix. Any ideas?