Could not save as <filename.PDF> because of a program error

I am running Photoshop CS4 Extended Version 11.0 on OS X 10.5.5. I have been trying to save a PSD file as a PDF and I've been receiving the dreaded "Could not save because of a program error" message. I tried rebooting, closing and opening the program, and saving to another folder or external drive and nothing works. Strangely, I was able to save a PSD to PDF file just yesterday. I have not seen a solution to this problem on a forum as of yet. Any ideas?

Robert,

System specs, including RAM and free drive space please.

Thanks.

Neil

I have 4GB of RAM and 824GB of available space on my hard drive.

can you save as PDF in a new user?