URGENT !! Having problems saving files !!!

I am having a serious problem with Photoshop CS, well serious in the sense that my college work has to be in tomorrow !!! BAsically I have several .psd and .gif files, which i want to edit, and for some reaosn all of a sudden when i choose Save as, and the pop up window appears 'Save' is disabled and i simply cannot save my work, or new work ?!
Does anyone have any idea what is going on here, I am totally stumped, and time is a tickin.

H

could you have features in the file that aren't supported in the format you're trying to save to? describe your file and what format you want to save in...

If you are saving as GIF, try the save for web feature.

For psd, you should be able to save to a different name. There might be some file-sharing protection going on. Change the filename later from Windows.