browser refresh shortcut F5 not working?

hello all,

I just received my new dell inspiron 15 inches laptop with Win 7 os...its great...

the problem I am facing is that the F5 key used to refresh the browser windows is not working...on my keyboard or keypad on the laptop,now the F5 key has a while symbol on it used to increase the speaker volume or contrast & nothing happens related to refreshing the browser...

can someone from dell or a dell user tell me whats wrong or is there any setting that needs to be taken care of?

thanks in anticipation

JD