Rendering artifact problem on scroll

[LivingDeadBeat]

Hi forum

I have built a forum manager and all is well and good, except there seems to be a problem with artifacts when scrolling the form. Screenies below:

This is what it looks like before any rendering problems



and this is what it looks like if you scroll about (mainly happens on older machines)



Does anyone know what the problem is? Its worse on some browsers and on older machines. Is there a way to stop this or reduce the risk of it happening?

Thanks alot

Tom