http://support.microsoft.com/kb/967715/

C:\>ipconfig /release

C:\>ipconfig /renew

AD Users and Computers -> corpX.un -> Properties -> Group Polices -> Edit -> Computer Configuration -> 
Software Settings -> Software Instalations -> New -> Package -> \\gate\share\Thunderbird.msi
Deploy software assigned

AD Users and Computers -> adcorpX.un - > properties -> Group Polices -> Edit -> UserConfiguration -> 
Windows Settings -> IE -> Connections -> Proxy Settings -> gate.adcorpX.un 3128

На целевом компьютере:

C:\> gpupdate /force

C:\WINDOWS\system32\clients\tsclient\win32