I have a similar, but different issue. This is the only thread that describes our symptoms, though.
Our users, for the most part, print to PDF without issue. However, in some cases, users will print to PDF, but over time will accumulate multiple processes (like, ten) of acrodist.exe that do not close on their own after the PDF is printed. After a while, applications will go to a (Not Responding) state, like the PDF printer is still working on printing the screen. We've waited for a good 20 minutes for the process to complete, but no dice. We've had success in ending the splwow64.exe process, but sometimes that doesn't even work. It's inconsistent. I've applied LaurieAnn's fix, and printing to PDF DOES work for a while, but continues to break after a couple of prints.
Am I onto something with the acrodist.exe creating multiple instances when there's only one PDF open, or am I chasing my tail?