Photoshop won't open

As of today, Photoshop CS4 won't open. When I try to start it, I see the blue circle going round for a few seconds, then it stops.
In Process Management a Photoshop CS4 will sit, using only 120 kB, doing nothing. I cannot end the process. When I try to start CS4 again, the same thing will happen and I have two copies of CS4 sitting in the process manager.

I tried to set my computer back to two days ago. To no avail. I then deinstalled and reinstalled Photoshop. Still to no avail. Anybody know what's going on?

Okay, I'll see how I update drivers. But how do I do that, from within Photoshop (which doesn't run)?

Anyway, I just managed to open Photoshop... from the default Windows viewer. It just won't open from the Start Menu. Still weird.

I'll see if I can update the drivers.

Okay, I updated from within Photoshop, that failed because I had two dormant copies of Photoshop sitting in my processes.
So I rebooted the computer, hit 'Photoshop CS4' from the Start Menu and it worked!

So thanks a lot!