Cursor always goes off screen like i have another monitor but i dont!

Hi,
I am having an issue with my cursor as it constantly goes off screen like i have another monitor (Extended Desktop) and it is really starting to tick me off! As I dont have another monitor how can i fix this issue?
This problem occurs when you go to exit a window or if there is something on the very edge of the window you need to click on (eg the scroll bar).
Please Help!!!

Sounds like the computer senses that there is a second computer
Using your computer manual, learn how to set up computer for second monitor and make sure it is off.
You can also try a system restore from one week before the problem.

It could be 2 things... Check incase you did actualy mistakenly click the extend desktop..

And makesure your desktop and monitor are not improperly set so as to be slightly too big.

I am at the monitors recomended resolution (1280x1024)
and when i got this computer it did not come with any manuals or anything i had to reinstall the operating system too because I got the BSOD and i could not recover the operating system. so it is now running windows vista home premium SP2

Check the actual monitor... It might be stretched out.. play with the buttons.... com'on you know you want to... com'on do it doit...