Crop tool missing/not active

I have Photoshop 5 running on Windows Millenium edition.

The crop tool is missing from the tool bar.
Also, when I go under the "Image" menu, the "Crop" selection is light gray and is inactive.

Why is this? How do I reset my settings so I can use the Crop tool again?

Thanks!

Click and hold on the marquee tool (uppermost, left hand side), you should see the crop tool.