Where's all my space gone?

A client's SBS2003 Premium server has started to alert us to low disk space on the C: which is bit odd as it shouldn't have been growing.

A quick download of the trial of Treesize Pro to see where the space is going highlighted an issue with the directory C:\WINDOWS\INSTALLER which had jumped to 7.6Gb - ow!

So how do we sort the installer problem - if you're very brave you could just zap all the files after taking a backup - not recommended.

The sensible solution is to use the Microsoft tool desgined to sort these installer problems, so d ownload the "Windows Installer CleanUp" utility from Microsoft at http://support.microsoft.com/default.aspx?scid=kb;en-us;290301 

Then from the command prompt run "MSIZAP G"

The G option tells MsiZap.exe to remove all orphaned cached Windows Installer data files