Dell Desktop: "Amount of system memory has changed, hit F1 to continue"?

On my main computer this has come up and I can't do anything with it, suggestions?

When your PC loads, The system speaker should beep.... If it does, How many beeps do you get when you get this message?

I hear two short beeps.

2 Beeps is usually down to the PC Memory failing, You may have to open up the case for a look yourself, If not this might help ya : http://www.computerhope.com/issues/ch000607.htm

If your still having problems drop me a PM and I'll see if I can find a solution for ya

Thanks very much, I will open it up and have a look at it later tonight.

as the actress said to the bishop!

Tut tut, have you nothing better to do than to find obscenities from me?

said the bishop to the actress!