Why does printing change font of document

Hello,

When I go to print a document off of either desktop laser printer or more industrial (big printer/copier/scanner/fax that is in a room of its own), at sporadic times, the font changes on the document (working in MS Word 2003/Windows Vista Basic). To get it to reset, I find I must shut down the machine as it affects the following documents that I pull up in Word.

Any assistance? Has anyone else experienced the same or similar?