Vista - SCVMM Error 3154 Details: Access is denied (0x80070005)

We have installed a new server 2008 box, running System Centre Virtual
Machine Manager 2007.

We are having a problem converting a physical machine to virtual. The
problem is not in isolation, and we have tested with trying to convert
an XP machine (SP2) and server 2003.

As soon as we get to the 'Gather System Information' things stop
working, and we receive the following error;

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An internal error has occurred trying to contact an agent on the
STUDAV.students.blackburn.local server.

Ensure the agent is installed and running. Ensure the WMI service is
installed and running, then restart the agent.

ID: 3154
Details: Access is denied (0x80070005)
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The job list indicates that 'Collect Machine Configuration' failed at
99%, with the other 3 tasks having completed 100%. I have retryed
many times, but the error appears exactly the same each time.....no
matter which PC or server I try to gather information for.

I have spent the last 3 hours investigating and googling, but havent
been able to find anyone else with the problem who posted a solution.

Can anyone help, and advise what our next steps should be?