Win 7 + Opus 11

I have 5 user licenses and have installed to 4 pC's so far (upgrading from ver 10). All bar one has installed ok. On the problem PC after installing the application would not run when double clicking the desktop. I tried disabling and enabling the setting without success. Opus has also been set to replace Windows Explorer (as had previous version). I have now discovered that the Control Panel application would not run as it was looking for Windows Explorer. I have disabled the replace explorer option and the Control Panel now works. Any suggestions on how to resolve this, all other PC's are ok?

From that description, I would first make sure that dopus.exe is not set to run in Compatibility Mode: Windows Compatibility Settings / Installer says XP SP3 is required on a later OS version