"Invalid font" error in PDF maker

For 12 years now I've been making my invoices in Excel and printing to PDF. I started doing it in Office 2010 and now have 2013. I have used the same font the entire time. Suddenly a week ago I couldn't print to PDF anymore. I get the message "Invalid font. Offending command: xshow. PostScript error. PDF file not created."

After much hassle I found that at least I could still save as PDF in Excel's Save as routine. Today I can't do that either. I get the same error message.

What has happened? Has there been some product update that screwed things up?