The question is which 'Omniback' folder did you save?
- The Config -> Server folder that has all the Backup specifications, the userlists, cell_information, licensing, all kinds of other good stuff
- The Server -> db80 which contains your Internal Database
Under NO circumstances should you put whatever you saved in place first, then install. Do your Installation, make sure that the base DP is running, stop it, rename teh existing 'omniback' folder, and put the saved one in its place
What would be ideal is if you had backed up the IDB onto tape before all this started