In the early 90’s we were preparing design documents that used Microsoft’s Object Linking and Embedding to bring the content of multiple programs together in one document. We found that linking worked fine, but embedding failed (it might have been the other way around, I don’t recall). So we called the Microsoft support line (which, believe it or not, had a live DJ on hold instead of canned music). When we got through to technical support and explained our problem, they asked us what our default Windows printer was. When we told them it was an HP xxx, they told us to choose a different default printer while we were performing the OLE operation. Sure enough when we changed default printer, it worked fine. Then we changed the default printer back and were able to print the document on that printer without a problem.
Now, as is the case for all software bugs there was a completely logical explanation, but the choice of a default printer wouldn’t exactly be the obvious place to investigate an OLE bug.