Sorry, you won't get any help. This is like calling your car mechanic and telling him/her that your car sounded weird yesterday for a while. You turned it off and then it was sounding fine. The mechanic, not having heard the sound and only having your description "weird" is not going to be able to guess what was going wrong.

Next time, at least take a screen shot.
This could have been hitting a very large zoom setting.
You could also use Shift+F12 (Save As) to save a copy.