Random bold text when printing from Adobe Reader, not Pro

Hello!

We have a problem with PDF files that we create in InDesign. Random text appear bold when we print them from Adobe Acrobat Reader. The problem is not present when we print from InDesign or Adobe Acrobat Pro. Some research I have done suggests a possible problem with transparency, but I don't think that can be the culprit here as we have the same problem printing a page consisting of only text and nothing else.

Does anyone have any idea what the problem could be?

Cheers,

Nils