I can suggest to copy registry files from another user for whom SAPB1 client is working fine and then try the wrapper for SAP Business One Client (but it has been tested only for client version 9.0).
Skybuffer SBO LogonPad (version 0.2)
The idea is that the wrapper will try to rebuild the registry files, but please be aware that it is a beta version and has been created just to facilitate SAPB1 consultants life 