Internal error occurred #3 (with a lot more internal error occurred related changes)

This commit updates a bunch of files and changes a lot of phrases. Basically it extracts "Internal error occurred" from existing phrases.
I've re-ordered the phrases so "Internal error occurred" is always at the end after the actual informative error message.

Example comparison before and after this commit:
Before: 1 Phrase: "Internal error: Unable to print to PDF"
After: 2 Phrases: "Unable to print to PDF." + "Internal error occurred"