Hello,
When you try to start Zimbra Desktop, does nothing happen (or at most a quick flash of a DOS box)? Zimbra Desktop seems to require Windows Script Host to run, and in my environment it's disabled by corporate policy (it can pose a security threat when used maliciously). You might want to check with your Administrator if you're in such an environment -- but if you aren't, or have administrative access on your PC and really don't care, try the following:
1) Navigate to x:\(windows folder)\inf
2) Locate WSH.inf, right click on it, and select "Install"
3) Attempt to start Zimbra Desktop again
If that solves the issue, super -- but if your corporate policy has WSH disabled, you'll have to do that every time you reboot your PC. There are ways to automate that via batch file on startup, so let me know if that worked and I can post the batch file I use.
Please note: I've only tested this method on Windows XP SP3, and am researching Windows 7 usage. Here are details on WSH via Microsoft:
What Is WSH?