I came across this today when decomissioning an Exchange 2007 in a 2007-2010 migration. After uninstalling the primary roles, it moves to removing the “Exchange files”, which are the Exchange Management files. At this point it will get stuck indefinitely and the timer will keep going. This is because a powershell commandlet gets stuck open.

To resolve: end the powershell(32) task and the uninstall will complete.

Source: http://support.microsoft.com/kb/959959