Running out of the diskspace on C:\ I found the C:\WINDOWS\Installer\$PatchCache$ to be massive! I used JamSoftware “treesize” to view what was taking up the space.
From research this folder can be safely deleted, however you MUST NOT delete the top level “Installer” folder “C:\WINDOWS\Installer” (only the sub-folders inside it)
A quick method for deleting this directory is:
Stop “Windows Installer Service”
net stop msiserver
Run the “Remove Directory” command (/q Quiet: /q | Removes all directories and files: /s)
rmdir /q /s %WINDIR%\Installer\$PatchCache$
Start “Windows Installer Service”
net start msiserver