@Tels. Thanks for your reply. For general purpose usage, the OSS driver is MUCH better than fglrx. Only the 3b performance is keeping it behind (but things there too seems to be improving lately, as shown by many recent Phoronix articles. ) I will try catalyst but my ultimate goal is to make sure it runs on OSS (because that is what I use). I was asking the question because I wanted to see if other users experienced the situation (if the issue might be in TDM). If it's a driver bug, then I'll report it and help in its debugging.