I have been having this issue for the last 4 months now.

I had ZD installed once on my system via the admin account, but used it with another user's account. After I noticed I cannot delete the attachments(that came from ZD) that have been stored on my desktop, without admin rights, I have removed ZD with the help of an admin.

Now, some time later, I am trying to get it to run again, to no avail im afraid.
Basically, I now have an admin account and all privileges associated with it. After I install either ZD 2.1 or 7b1, and then click on the desktop icon. Nothing happens. Zimbra does not start, nothing at all happens. The mouse icon does not even change to tell you that "something is being done".

This happens on both versions.
I have installed the following to ensure I am not missing any prerequisites:

Net Framework 4
C++ Redist (latest)
Java (latest)

My Zimbra related locations:
C:\Users\[user]\AppData\Local\Zimbra\Zimbra Desktop
C:\Program Files\Zimbra\Zimbra Desktop
C:\Users\[user]\AppData\Local\VirtualStore\Program Files\Zimbra\Zimbra Desktop (this only has a empty prism folder inside)

Any suggestions what might be wrong?

Many thanks in advance.