It usually in the result of a misconfigured Rainbow Sentinel Driver. You can access that in the Omega Group.
If that doesn't do it, you will get it straightened out the quickest if you go to 4EdgeTalk.com, register and then do a search on
Windows XP and Parallel Ports. it was discussed in some depth there but I don't recall the conclusions at ths point.
Just curious ... are you sure you are running Omega 2.2. As far as I know the 2 series topped out at 2.1.0.19. Version 2.5 was just released today.