An advanced InfoPath client of mine was working in InfoPath 2007 the other day and suddenly, all his toolbars disappeared. Even the toolbar with the File menu on it was gone. The only thing that showed up in design mode was the task pane on the right.
After talking with him, he told me he had repaired and uninstalled/reinstalled InfoPath but the problem remained. After searching around the registry and thinking that I might have found something at HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Common\Toolbars\Settings\Microsoft Office InfoPath, through trial and error we found that that key didn’t have any effect on the missing toolbar problem.
I had him log on as another user and start up InfoPath and the toolbars were there, so it certainly appeared to be a user settings issue. I found this article about Excel 2000 and decided to poke around and see if InfoPath had the same type of toolbar settings. Sure enough, in C:\Documents and Settings\[UserName]\Application Data\Microsoft\InfoPath there is an infopath.tbs file. After renaming this file and restarting InfoPath the toolbars reappeared.
Don’t know what happened to corrupt this file, but now we know how to fix it.