I have had funnies with my system recently, not just with PSE.
In my case it turned out to be a hardware/driver problem.
What operating system are you using?
What is your workflow when adding the captions (there are many ways to do it)?
Could it be a sticking key on the keyboard - How do you move from one photo to the next?
Due to various problems, I have been using the Private Message facility to help JLynnette.
The rolling problem occurred when clicking on the down arrow in the scrollbar to advance to the next photo. The workflow has now been changed to using the down arrow on the keyboard and all is now well.
Windows 7 was being used.