DrawPixels Artifacts

Have been developing a new app for a client which works on a dual display, just through windows extending the desktop over 2 monitors. Not sure if thats relevant yet but… creating an im age and using draw pixels but get a diagonal artifact and some banding on the clients computer. Have no idea why though? -> http://users.cs.cf.ac.uk/G.R.Powell/banding.jpg

hardware/OS/drivers ?
To me it looks like a bug in driver/card implementation.

Does it happen only on dual display ?

well it works fine on my single display, i will find out tomorrow how it works on the clients with a single monitor. Assuming it is driver/card apart from finding a patch is there anything that can be done? I guess not until they release an update?

weird but… artifacts only occur at specific window sizes. so when resizing with each minimal width change it goes from ok to artifacts

has anyone else found this… if the winow is ‘odd’ sizes then we get artifacts, if its even sizes (only in width) then its fine. new card, updated drivers, fine on all other cards/comps. fix being go fullscreen but only at even width screens is a simple fix. strange! obviously a float div error somewhere?? never had that before.

You still did not post what graphic card has this problem.

off the top of my head i believe its a ATI Radeon X300 SE, but i would have to check