ATI HD5670 Display problem?

[SEE]

This is a new 'Saphire HD 5670 512Mb' that I have installed into a new PC running XP SP2. Apart from some screen tearing (which I don't get with my Nvidia GTS250 fitted in my other PC with Identical hardware spec) I get a band of green squares across the top of the desktop screen when I close IL1946. I have installed Catalyst 10.8 (for XP) but maybe some one could shed some light on why it is doing this or if its a faulty card?

I'm running in 'perfect' OpenGL and have set the Video Tab to 'Maximum settings' in the IL1946 set up utility as the HD6000 series is not listed in the Graphics card support list. If I open an application and then close it the band of green squares dissappears (they look like a series of miniature screens). I don't want to return it if its simply a set-up problem.

If anyone is using this card I would appreciate any info on how they have it set up with IL1946. I haven't changed any of the default setting in the Catalyst CC.