Today I had a strange error while trying to save an image in Photoshop 7.0. The image was opened as a JPG and I was trying to save it as a regular PSD file.
It turned out that the JPG image must have some corrupted metadata. The solution was to go to the File | File info... dialog and uncheck the field labeled: Preserve Additional Information prior to saving.
Sometimes, Photoshop can exhibit unexpected behavior.
One of the solutions is to try to reset the Photoshop Preferences. There are various ways to do it, as outlined here. One way is to hold Alt, Ctrl and Shift keys while the application starts up. You will be asked if you want to delete the Adobe Photoshop Settings File, to which you should answer “Yes” if you are sure you wishlike to have it deleted.
You should also take note, that this means resetting all your settings and preferences to “factory defaults”.
Save For Web
If the problems are only present in the “Save For Web” dialog try holding Ctrl+Alt while selecting Save for Web from File menu. You should be then shown a dialog enabling you to clear the Save For Web preferences. This may not work in all versions of Photoshop, as described here.