Re: I ditched 7-Zip...

You sure you're using the version of 7-Zip that corresponds to the architecture of your OS? Installing the 32-bit version of 7-Zip on a 64-bit version of Windows will result in shell integration problems (as I witnessed back in the early days of 64-bit computing. Ran XP Pro x64 on one of my rigs, but at that time 7-Zip was only available in 32-bit). Shell extension started working properly once they came up with 64-bit native versions of 7-Zip.