Make sure that when you reinstall the program (or run the workstation setup), you have appropriate installation rights to the \windows and \windows\system32 directories. Adagio installs it's own proprietary fax driver under the Windows Printer Driver area. If you are logged in as a user without those rights, that could be a cause here.

Note that you do not have to have any other Windows Fax system installed in order to use faxing in Adagio. We install everything you need.