OS: Windows 7
The Windows Explorer integration is broken in Windows 7 on 2.12.4. It took me a while to track this down. The bug presents itself if you install WinMerge 2.12.4 with Windows Explorer integration. If you attempt to create a new folder by clicking the New Folder button in an Explorer Window, you get an access violation and crash. This issue seems to be caused by ShellExtension.dll!DllUnregisterServer
Not sure if the new version has this same issue, but it is worth checking out.