After having no success in installing an earlier version of ZD 7.1, and after receiving no forum answer on how to fix the problem, I decided to try the latest version, mostly because it is now supported by VMWare.

Before uninstalling my old version, I thought I'd try to install ZD 7.1.4 on a VM in VMWare Workstation 6.5.4. When I run zdrun.vbs, I get the error:

Script: C:\Program Files\Zimbra\Zimbra Desktop\win32\zdrun.vbs
Line: 85
Char: 5
Error: This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem.
Code: 800736B1
Source: (null)
There is no log file.

There is another unanswered post about this problem--Error when starting Zimbra, refuses to run--so I am starting a new thread.

Some details about the VM:

XP Pro Sp3
583MB physical memory after installation
.NET Framework 4 Client Profile + Extended
.NET Framework 2
I could find very few requirements other than 512MB memory and 200MB disk space. What, if any, other requirements are there? What is causing this error? How do I fix it? I want to get this working in the VM before I destroy my existing installation and install the new version. I have exported all mailboxes.

OK, I solved this and am leaving this thread up for others having the same problem.

In the Event Viewer->System, there is an error that is the likely cause:

SideBySide Error None 32 N/A Dependent Assembly Microsoft.VC80.CRT could not be found and Last Error was The referenced assembly is not installed on your system.
A Google search reveals that this error is caused by the Visual C++ 2005 Redistributable not being installed and that you have to install it AND SP1:

Microsoft Visual C++ 2005 Redistributable Package (x86)

Microsoft Visual C++ 2005 SP1 Redistributable Package (x86)

I first came across the 2008 versions of this and installed them and they did not prevent the error. I uninstalled both of them and installed the 2005 versions and it now works perfectly! For the first time in years, I can now send emails, not just receive them, from my free Yahoo accounts from ZD.

Frankly, I can't believe that: A. there was no mention of this requirement in the installation document, B. that a version as old as 2005 is required and that it won't run with a newer version, and C. no one could tell me this when I had the problem before. Someone needs to fix this.