[scribus] "Cannot write to file" when exporting as PDF

[Bob Furber]

Forgive me for asking a question that must have been asked many times 
before:

I have been happily using Scribus 1.3.3.14 (on Vista) for a couple of 
weeks and sent our first newletter to the printer earlier this week, as 
a PDF file generated by Scribus.

However, today, when I went to generate (Export > PDF) a medium 
resolution PDF for our website, Scribus told me "Cannot write file: 
path/filename.pdf. I repeated the exercise at the resolution I had used 
previously and I got the same error. I can Export as PNG or EPS, but not 
as PDF, even after deleting previous PDF with same name.

Both our print shop and our website require PDF files. Is there a solution?

Thanks,

Bob Furber