Sorry for the trouble this is causing. Off the top of my head, the only thing I can think of that would cause this is one of the entries in the "Style" preference pane accidentally getting a "make hyperlink" style added.
If you open that pane in OmniFocus' preferences, is the "Reset" button in the lower left active? If so, and if you're not using any custom styles you want to preserve, pressing that button will likely clear that up.
If you are using custom styles, or if resetting the styles doesn't fix this, email the
support ninjas and we'll be happy to help. Apologies again!