I used to have SAPGui 7.3 and NWBC 4.0 installed on my laptop on Windows 8.1. When I upgraded to SAPGui 7.4, I chose the option of installing NWBC 5.0 altogether. When I lauched the SAPGui 7.4 for the first time after the upgrade, I got an error message like:
So I had to uninstalled everything including SAPGui and NWBC and do a clean installation from scratch. After the installation, I can open SAPGui 7.4 successfully but still had problem with NWBC 5.0. The NWBC startup window poped up then closed without any error message. So I checked the 2066345 – NWBC for Desktop 5.0: Prerequisites and restrictions and made sure the software requirements were met on my laptop.
Eventually I downloaded the NWBC500 patch level 2 from SMP and it solved the above issue.