Sunny,
Had the same problem when we upgraded 2 weeks ago. Turned out to be a windows issue. We had to change the setting for data execution prevention. It gives you instructions on how to do this on the clients in the web admin guide, but we had to do it in the server as well. The registry setting didn't work for us either.
Go to My Computer, right click and select properties
Select Advanced Tab (2003) or Advanced System Settings (2008)
Select the advanced Tab
Select Settings under the Performance heading
In the Performance Options select Data Execution Prevention tab
Select Turn on DEP for essential Windows program's, it was probably set for ALL option hence you isssue
Click Ok
As soon as we did this the CUEAC service went active but Just to be sure we restarted the server, but restarting cueac services may be enough
Hope this helps
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