For some unknown reason, my image file associations in Windows Explorer keep getting undone, such that they show up in Explorer without an associated application (or occasionally with a wrong association). For example, when I examine the properties of any .jpg file, the "Open With:" property says "Unknown application". My default image file viewer application is ACDSee Ultimate 8, and the registry key for .jpg files looks like this:Code:[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jpg] [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jpg\OpenWithList] "MRUList"="a" "a"="ACDSeeUltimate8.exe" [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jpg\OpenWithProgids] "ACDSee Ultimate 8.jpg"=hex(0): [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.jpg\UserChoice] "Progid"="ACDSee Ultimate 8.jpg" However, as I say, that never seems to get propagated from the registry such that Explorer will correctly open ACDSee when I double-click an image file (ALL image files are the same, not just .jpg). The question is: WHY? I've tried creating a .REG file that contains all the correct registry settings, but when I merge it, nothing actually changes! And naturally I've tried running the following command to force the registry to be freshly loaded: C:\Windows\System32\rundll32.exe USER32.DLL,UpdatePerUserSystemParameters ,1 ,True But nothing seems to work! I trust you've seen that I'm a very knowledgeable user who is not struggling with primitive questions, but I'm at a loss. What, exactly, am I doing wrong? What do I have to do to FORCE a change to all the file associations such that they'll open in ACDSee when I double-click them?