CCleaner should remove C:\Users\All Users\Microsoft\Installations
In my computer it contained gigabytes of setup kits of old W.I. software I installed over the past months.
Hm... I thought CCleaner already cleaned up after installs...
I would tend to agree that if this isn't done CCleaner should absolutely perform this cleanup so long as those files aren't needed for something. For example I know that Windows updates sometimes make backups so that you can go back to a current version (i.e. remove the update). I don't know enough about how Microsoft handles Windows updates to know for sure the necessity of these files. Hopefully someone from Piriform can shed some light...
Thanks,