I had the contents of my (dying) ibook transferred onto my emac. The tech created a new user/desktop on the emac. Now, when I try to open PDF files from a website, I get a drop down window saying this:
"Downloading - users/myname/desktop/xxxxx.pdf could not be saved because an unknown error occurred. Try saving to a different location."
Points to note: 1) The "xxxxx.pdf" part of the above message changes each time I try to open a pdf document, even the same one, and it does not show the real name of the document (e.g. CollegeApplication.pdf). The xxxxx.pdf is usually written as gibberish, like "86hgkjh.pdf" or "sdfj99f.pdf."
2) this never happened on my laptop;
3) the settings are set in Firefox to download pdf's to my desktop;
4) I have the latest version of Adobe Reader, which I already tried opening before downloading;
5) the settings are also set to open pdfs using adobe.
I had the same problem when I installed Firefox 3, but I think the problem is due to my recent hard drive upgrade. Try changing the download location from "Desktop" in Microsoft Internet Explorer and all other browsers (Safari, Firefox, etc.) to whatever default location you prefer. I never use Internet Explorer, but I think somehow my settings were corrupted when I upgraded my hard drive. I found this solution on another site also.