pdf conversion problem

I have used the pdf conversion feature several times, successfully and unsuccessfully.

More than two weeks ago I entered a pdf file, and the "system" has been chugging away in an attempt to convert since then, without producing either a successful or unsuccessful result.

I have tried to stop/cancel/delete/etc the pdf without success.

While the current pdf is attempting to be processed, the "system" will not let me enter another another pdf for attention.

Suggestions welcome.

Art Schubert