Unable to Register Error Message

I have installed RoboHelp, using instructions from other messges to this forum, by ensuring that I was logged onto the PC with full administrative privileges when installation occurred. I then launched RoboHelp HTML and RoboHelp Word whilst I had the full administrative rights. Everything worked OK until the administrative privileges were revoked and I tried to launch RoboHelp again. The error message "Unable to register hhctrl.ocx, itss.dll, RelatedTopicControl.ocx, CloseWindow.ocx, HHCTRLVersion.ocx, Index.ocx, etc....." appears. The IT department and I have uninstalled and re-installed the application several times following these steps, but we still receive this error message. From what I read I should not require continual administrative privileges (and I won't get it anyway in my organisation). Is there another step that needs to be undertaken?