problems with photoshops liquify

Hi all... I used to use liquify on photoshop but for some reason it no longer works! I thought it may be my ram so I put another 512mb (gig memory now) and I brought myself a new lcd screen "well it was a good excuse to justify gettiing one lol" but still no liquify. I use photoshop CS2, Any ideas ?

....as in: the Liquify window doesn't even open or, once open, the tools don't work?

Have you tried resetting Photoshop's Preferences (as per the FAQs)?