Usually that means a bug in the video card driver - and updating the driver from the GPU maker's website (Nvidia, AMD/ATI, or Intel) will solve the problem.
If you can't update the driver for some reason, disable GPU drawing in Photoshop's preferences, then restart Photoshop.
How have you got on with this one Dawn? Vista is so flakey, it might want to fight you all the way.
I'm guessing that a system running Vista is going to be old(ish) and low spec, but Windows 7 was billed as being the first MMS Operating System that needed less resources than its predicessor, so it _might_ be worth looking at putting Windows 7 on the computer, but only if there was little or no cost.
This link dates back to 2010 but it might work for you
Problem with that Trevor, is that Vista, windows 7 and windows 8 are all the same version. They are only point upgrades. So in a sense when 7 came out, the bugs were fixed.
And in reality, it proberly isn't worth throwing dollars at a system that was built when Vista was around. I'll get into trouble for saying that from all the XP fans that post here