Alright, I might have come up with a fix for why coherence won't install during the upgrade from 2.5. I installed a new VM w/Tools successfully. I compared the offending Parallel Tools directory with the successful install, and noticed there was 3 files missing and 2 additional from the 'not worky' one. The missing files were coherence.exe, menuhook.sc, and prlhook.dll. The additional files were Plug-Ins service and pcit3bea.rra. So (and I am not claiming I cured cancer here) I made the directories look the same and re-installed Tools in the VM I was having the issue with. The complete install went through, I restarted, and now coherence is back.
