Double-click won't start programmes

I use Win 7, and just upgraded from 32-bit to 64-bit.

The upgrade has been pretty successful (I used PCMover which helped a lot) and most things are either working as they should, or I know what I have to do to fix them.

However when I double click desktop icons I am moved to Direcory Opus (my WinEx replacement) instead of the programme starting. I have to right click and choose "open" to run the programme.

I'm sure there is a fix for this - I looked in Regedit at the mouse setup, but that seemed fine. If anyone can suggest a solution, I will be very grateful.

Here is a "Sysinfo" log:

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Professional, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz, Intel64 Family 6 Model 23 Stepping 6
Processor Count: 2
RAM: 4028 Mb
Graphics Card: NVIDIA GeForce 8600 GT (Microsoft Corporation - WDDM v1.1), 256 Mb
Hard Drives: C: Total - 715394 MB, Free - 91903 MB; F: Total - 305234 MB, Free - 283622 MB; J: Total - 1430796 MB, Free - 1048993 MB;
Motherboard: Intel Corporation, DG43GT
Antivirus: Norton 360 Premier Edition, Updated and Enabled