The symptom is this: When attempting to save a page as a Web Archive file, using the Save As... command, Safari fails to cooperate. Instead, it gives you an error message stating that "The document...could not be exported."

Fortunately, this doesn't happen all the time. It occurs only sporadically, with some Web pages but not others. So far, I have been unable to figure out what exactly triggers the error. My first theory was that it had to do with the auto-generated name of the to-be-saved page. However, no matter what I did to edit the name, the error persisted.

In the end, the bug may not be linked to specific pages at all. In one case, I managed to circumvent the problem by quitting Safari 4, relaunching it and selecting "Reopen All Windows From Last Session." The previously unsavable page now saved without a hitch. Go figure. This didn't always work, however, so don't count on this as a sure-fire solution. When it does fail, my other main work-around is to save the file as a PDF (via the PDF -> Save as PDF option in the Print dialog).

Less often, I've seen a second bug involving saving pages with Safari 4. With this one, you get an error message that says: "You cannot save this document with extension '.com' at the end of the name. The required extension is '.webarchive'."

Again, this message only appears sporadically, apparently at random. As far as I can tell, I am making no attempt to use .com at the end of the name, so it also makes no sense. The good news is that there is a much easier solution here than for the previous bug. The error message includes a button to "Use .webarchive." Just click it and the page is saved.