erratic html display behavior

The html display behaves erratically in all of my projects, whether existing or newly created. Large spaces appear at random in the html (not in the Design window). The odd behavior first appeared when I was editing a topic on the html screen. The characters move around the screen as I am typing. It’s almost as if I am “chasing” the characters around the screen. Simply placing the cursor on the screen causes the characters to reposition themselves. I’ve looked for a setting that could be causing this strange and seemingly spontaneous rearrangement, but nothing I’ve tried seems to make any difference. I’ve also removed the application and reinstalled it, to no effect. I copied one of my projects to a server and had a coworker open it, and the html appeared normally on her machine. I also opened a project from the xpj file instead of from within RoboHelp – no difference.

I am using RH v. 7.00.145