The newer drivers are signed with SHA256 as well so it could be tripping up on those two since by default Windows 7 (including SP1) does not process them. If so a simple (but potentially long) fix would be to update your Windows 7 Guest and try again. If you don't mind a little manual work you could go the Microsoft Page regarding the addition of SHA2 support here and find the related files for your version and download them from the catalog and manually install just them skipping the 'full update loop' on a new Windows 7 guest...but it normally is a good idea to fully update if the VM will be used long term.
Failing that helping as you mentioned an 'upgrade' it might related to a previous version of the same driver not being uninstalled cleanly. I'd try to do a full tools uninstall followed by a reboot then check to ensure that the "C:\Windows\System32\drivers\vmci.sys" is actually removed during the uninstall.
If it still won't install the newer tools it might help if you look through or attach the logs related to the failed install attempt for more details about WHY it failed. The logs can usually be found in the standard temporary directories such as %TEMP% or %LOCALAPPDATA%\Temp
