Exchange 2010 Uninstall

I am trying to uninstall a test environment installation of Exchange 2010 and reinstall fresh as there were some configuration inconsistancies in the original installation and would prefer to have all the proper configuration in place rather than troubleshoot the configuration.  My attempts were made through add/remove programs and clearing the check boxes next to all available server roles and the management tools.  I receive the following error when it tries to remove the mailbox role and I can't continue:

Summary: 10 item(s). 1 succeeded, 1 failed.
Elapsed time: 00:00:07


Preparing Setup
Completed

Elapsed Time: 00:00:03


Mailbox Role
Failed

Error:
The following error was generated when "$error.Clear(); $a = get-wmiobject win32_operatingsystem; if( ([int]($a.version.split(".")[0])) -lt 6 ) { stop-SetupService -ServiceName HTTPFilter }" was run: "Not found ".

Not found

Error:
The following error was generated when "$error.Clear(); $a = get-wmiobject win32_operatingsystem; if( ([int]($a.version.split(".")[0])) -lt 6 ) { stop-SetupService -ServiceName HTTPFilter }" was run: "You cannot call a method on a null-valued expression.".

You cannot call a method on a null-valued expression.

Elapsed Time: 00:00:04

Are there specific steps that need to be taken prior to removing Excahnge in this fashion or a better way to perform the uninstall?

TIA