Over the past few days my computer has started freezing up to the point where I have to shut it down completely after I open Microsoft Word.

Everything will be completely fine (like it is right now) and I'll open Word either out of habit (I usually have it open) or something I'm viewing online has a Word attachment and my computer will completely freeze up after a while. I can sometimes switch windows but if I go back onto Firefox, the computer is unbearably slow and goes through periods of freezing up.

So what is the problem? What is causing this? I haven't installed any new hardware (I keep getting a disk consistency test at the beginning of these boot-ups which I didn't before). It just came out the blue. Any help would be greatly appreciated.

By the way I am running Word/Office 2007 on the computer.