Contact Merge Freezing at Submit Frame

When I try to merge contact records, I pull up one of the records, go to "more actions," click on "find and merge," mark the contacts I want to merge, make any changes I want to, then click "merge."

Then the screen goes dark, and I can't click on the "submit" button. The screen freezes that way until I hit the back arrow. The records are not merged.

Thank you.