Adriano Chiaretta

Ever run into problems with Windows Service Packs or other updates failing to install? Msizap can save the day by cleaning up leftovers from previous installations / uninstallations.

If the size of your c:\windows\installer (or wherever you have your ms op sys installed) is over 3 GB chances are you need to perform some spring cleaning with msizap — which is a command line tool included in the Windows Installer CleanUp Utility

Once installed, get to a command prompt window, and navigate to the installation folder. Launch:

msizap !G

to have the tool remove any orphaned files from the above mentioned folder.

Launching msizap.exe without parameters will list its various options:

MSIZAP – Zaps (almost) all traces of Windows Installer data from your machine.

Usage: msizap T[WA!] {product code}
msizap T[WA!] {msi package}
msizap *[WA!] ALLPRODUCTS
msizap PWSA?!

* = remove all Windows Installer folders and regkeys;
adjust shared DLL counts; stop Windows Installer service
T = remove all info for given product code
P = remove In-Progress key
S = remove Rollback Information
A = for any specified removal, just change ACLs to Admin Full Control
W = for all users (by default, only for the current user)
M = remove a managed patch registration info
G = remove orphaned cached Windows Installer data files (for all users)
? = verbose help
! = force ‘yes’ response to any prompt

Note that the only one safe to run is “G”. Everything else is rather dangerous / drastic and will likely cause more harm than good unless you really know what you’re doing. More info on this tool and handy howto available here.