Alt tab flicker problem

I hold down alt + tab
If I don't do anything in 1/2 a second, it dissapears!

This is winding me up
Why is this happening

I've googled and the people have said the problem is to do with a static keyboard - the problem happens both with the keyboard AND and external USB keyboard plugged in

Other suggestion say that the graphics driver needs updating
My laptop is 5 years old - I have the last update of the graphics driver installed already

I've never had the damn problem until yesterday!

Why has it JUST come up...?
What could have caused it?

Grrr.... I just can't use anymore!!

Help

Thanks


OM