[SOLVED] Preview Button Stopped Working

I am guessing that you won't be able to help, but I am going to try anyway! :-)

Suddenly my Preview button on the Edit Post page in Atahualpa stopped working. I can still see a preview by clicking in the appropriate place from the Post list, but can't figure it out. It was working earlier today.

I was earlier trying to change the image in my header and clicked on something that when I did it it said "fatal error" so I am wondering if I did something, though it doesn't seem to make sense that a header image error would affect the Preview button.

The only other thing that I can think of is that I am still using 3.0.4. I have been nervous to upgrade since I don't know how to backup my blog yet.

Again, I suspect this is not the cause but thought that the information might be of use.

Thanks in advance. http://wholenewmom.com