This is a lot of trouble just from an install. Installing another program will sometimes replace older versions of shared files but the REGSSI.DLL is a Softrak DLL; it is unlikely that the install removed or replaced it.

The message regarding Reporting tables probably indicates that the path to the QRASP is not correct. For Quik Invoice for Windows, the path is set in the CRW.INI. This file is in the Windows directory under the section Accpac.DLLInfo.

From the errors, I would have guessed that a workstation setup had never been done. A reinstall and then a workstation setup on the second station will correct the errors.