Problem with pc?

[klute]

Hi all need some advice....after putting my PC on standby if i later return and tap a key to start things up again i get a black screen that can last 5 minutes before revealing my desktop sometimes brighter with a washed out look or as a couple of days ago a light greenish colour.
Sometimes if i then switch off the pc my monitor stays on and i have to switch on and off a number of times before the monitor goes back to standby.

It hasn't always done this and i'm wondering if anyone else has has the same problem is it the graphics cards/drivers/monitor or something else???

I can't to the best of my knowledge find any problems with the monitorGFX cards/pc so i'm puzzled and don't really want to take it somewhere to get fixed if it's something i can fix myself IE if it's a driver/program or even the standby settings

I'm currently running Vista and have done for a number of years despite having windows 7 available

i have 2xNvidia geforce 8600 gs's

[Professor Bear]

Could be a graphics card problem, as they don't always fail catastrophically (blue screen/restarts) and can manifest failures initially in the form of small-scale screen corruption as you describe.
Although I prefer to blame Vista.  Saves time.