Windows wont close

Whenever I go to close one of my open windows, it wont.
Not even if i press the X at the top right hand corner,
all it does is flash and the only thing I can do is
minimise it. I end up having to restart my computer to
get rid of them. HELP!!! this is soo annoying!!!!

Hold down the Alt key and press F4


>-----Original Message-----
>Whenever I go to close one of my open windows, it wont.
>Not even if i press the X at the top right hand corner,
>all it does is flash and the only thing I can do is
>minimise it. I end up having to restart my computer to
>get rid of them. HELP!!! this is soo annoying!!!!
>.
>