Liquify Tool has gone bugged.

I have Adobe Photoshop 7 on the PC, and I'm not sure what's happened, but recently my liquify tool has gone bugged. When I use a tool on an image, all I see is a 'block' where the cursor is, which prevents me being able to view what the liquify tool is actually doing to my photo beneath this 'block'.
Do you know how I can fix or reinstall this built-in feature of Photoshop to get it working again? Many thanks in advance.

The only thing I can think of based on what I've read here, is vid drivers. As a test, go to control panel, run the system applet and look for Video Hardware Acceleration, and set it to NONE. Then try your liquify. If it goes away, you need to either update or roll back a version of vid drivers.

Peace,
Tony

Hi Tony, thank you for the reply. That seems to be the problem - it doesn't like my Nvidia driver. I'll see if I can hunt down an older version of the driver!
Thanks.