I have installed 7-Zip on my machine and associated it with serveral archive file types.
When double clicking an archive (so far I have tried .zip, .7z and .bz2 files), a message box pops up telling me that 7-Zip cannot open this file as an archive.
However, when I right click the file and select 7-Zip->Open as archive, it works just fine.
All the file type are associated to 7zFM.exe, the 7-Zip File Manager (as opposed to the 7-Zip GUI or command line).