"save as" dropdown closes immediately

A week or so I started having problems with the Save As panel (the second one - where you can put in the filename of the PDF file to be created).

If I try to use the "Save in" dropdown to select which folder to save into, the dropdown opens and then immediately closes. For instance, it "Save in:" show "My Documents" and I want to put it on another drive (my S: drive) the dropdown opens and then immediately closes. I can't pick another drive (or for that matter, anything except for "My Documents" or one of its subfolders.

(I'm not sure this problem is unique to PDFCreator, but it does work in some applications - such as saving a MS Word .doc file in another place.)

Any suggestions.

Rich