Concept 2.6 XL and GE iFIX 5.5 IGS OPC - "Illegal Modbus Function Call"

I have a laptop running Windows 7 OS, and has Concept 2.6 XL, iFix 5.5 and IGS 7,56 OPC.

The Concept software is used to connect to a simulated Momentum PLC via TCP/IP or IEC Simulator. Data is interchanged between the PLC and iFix via IGS.

My problem is that I cant even get the Concept to connect to the PLC. I get this error "Illegal Modbus Function Call Error Id: OL9-21581" every time i attempt to connect. I am thinking Concept is trying to connect via Port 502 but 502 is being used by IGS hence the "Illegal Modbus Function call". If i disable all the IGS services or assign IGS to another port, Concept will connect to the PLC, but then IGS will not communicate with the PLC presumably because it's not able to connect via Port 502. I need both to communicate via port 502.

Schneider Support claims Concept 2.6 XL does not support Win 7. But this was all working on WIn 7 before!!