A simple solution for you may be to use the Alt+Tab keys. This will allow you to switch between windows if the taskbar is messed up somehow.
If you are still determined to find the real solution to the problem then please follow this more detailed version of the steps I posted before (this will allow you to upload a picture of your screen).
I' ve used the key and nothing shows on my screen, probably not using the key correctly.
Nothing should show up when you press the key. That's why you have to open paint and paste it in.Here's what you should do:
1) Press the PrintScreen key
2) Click start->all programs->accessories->paint
3) Press Ctrl+V
You will now see your screen inside of paint
4) File->Save As
5) Login to this site and post new message
6) Click additional options under the message field
7) Browse
Find the file you saved
I don't mean to sound condecending here, if you already know how to do this stuff.