Target OS: Windows
Purpose: Google Calendar Sync seems to cause Outlook to restart everytime it syncs when Outlook is setup with the Zimbra Connector
Note: Another Relevance clause could be added to detect the Zimbra Connector to only have this fixlet relevant on machines where the problem may occur. In its current form, this is just a generic uninstaller for Google Calendar Sync.
 

Relevance 1:

(name of it = "WinXP" OR name of it = "WinXP-2003" OR (name of it = "WinVista" AND product type of it = nt workstation product type AND NOT x64 of it) OR (name of it = "WinVista" AND product type of it = nt workstation product type AND x64 of it) OR (name of it = "Win7" AND NOT x64 of it) OR (name of it = "Win7" AND x64 of it)) of operating system​​​
 

Relevance 2:

exists value "UninstallString" whose (it as string as lowercase contains "uninstall.exe" as lowercase) of key whose (value "displayname" of it as string as lowercase contains ("Google Calendar Sync" as lowercase) of it) of key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" of registry​
 

Action:

// Close GoogleCalendarSync.exe
waithidden taskkill /F /IM GoogleCalendarSync.exe
continue if{not exists running application whose (name of it as lowercase = "GoogleCalendarSync.exe" as lowercase)}
 
// Close Outlook.exe
waithidden taskkill /F /IM outlook.exe
continue if{not exists running application whose (name of it as lowercase = "outlook.exe" as lowercase)}​
 
wait {value "UninstallString" whose (it as string as lowercase contains "uninstall.exe" as lowercase) of key whose (value "displayname" of it as string as lowercase contains ("Google Calendar Sync" as lowercase) of it) of key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall" of registry} /S
 

References:

http://nsis.sourceforge.net/Docs/Chapter3.html#3.2