A user who loaded the latest PSX, could not open it after install. The program showed momentarily in the task manager then disappeared, no flash screen or any message. We established that the PSX install looked good.
During the process of switching items on/off through msconfig, they realised that it was down to a product they had installed called StarDock. This has a Windows theme manager that grabs an opening window and applies a theme to it.
When he added PSX.exe to the Exclusions list under its settings, all came good.