Issue with pop up instruction window...

I just installed Acrobat to fill out an IRS form...when I check a certain box on the form, an insturction window pops up (I'm checking a box, not hitting a question mark for help). There is no way to X out of the box and I can't continue filling out the form. It won't let me scroll down to the bottom of the box to his close. I've tried everything I know to do. I keep having to shut my whole computer down because I can't even get Acrobat to function at all when that window is up. Anyone having this issue?