One day I was able to print to PDF (using Adobe Acrobat 9 Pro & 10 Pro distiller) and the next day I wasn't. After a week and a half of research by myself and two of our IT folks, we uncovered the problem.
When I printed from Revit to PDF, I would get the following error message:
[ ProductName: Distiller ]
[ Error: undefinedresult; OffendingCommand: imageDistiller ]
[ Flushing: rest of job (to end-of-file) will be ignored ]
[ Warning: PostScript error. No PDF file produced. ]
I could print to PDF from other applications (Word, etc), just not from Revit. The problem persisted over multiple machines and over multiple files.
Our IT department pushed an Adobe update AND a Revit update. Not sure which (if either) of these changes caused the issue.
In the Adobe print settings (Start > Printers and Faxes > Adobe PDF Properties) go to the Advanced tab and ensure that "Enable advanced printing features" is checked. Mine wasn't. Enabling it solved my print-to-PDF problem.
I hope that this post saves somebody else the week-and-a-half headache it caused me.