"The task scheduler service has asked the task to run"

Hi guys,

I am trying to wean my endpoints from a server running SEC 5.1 to SEC 5.2.1 running on Windows 2012.

All of our servers (and IT department PCs) accepted being "re-protected" from the new server and are now updating normally.

However, for the majority of our staff PCs (all Windows 7), I am receiving the following message

"The installation could not be started. The task scheduler has asked the task it run. The computer may need additional configuration before installation"

This is a surprise because the 5.1 server seemed to manage OK and the same GPO is still applied.

I have checked and the GPO, as per the sophos instructions (for a 2003 domain), does the following:
* Set the remote registry and task scheduler service to 'automatic' and windows installer service to 'manual'

* Configure the windows firewall to allow remote task scheduling, file/printer exception

* Open Port 8194 incoming and outgoing

The way I have managed to successfully deploy sophos to some of these affected endpoints is to remotely start the windows installer service before selecting to protect them from the console. I went back to the GPO and changed windows installer from manual to automatic, but this did not cause the service to remain in the started state.

If anybody has come across this error and has any advice, or just need any further background to my setup, pleeeease get in touch!

Many thanks,

Liam