I just encountered this issue in a completely different context, but I figured I may as well add the information in this thread if it can help anyone.

The RPC_E_CALL_REJECTED error occurs when some applications (notably MS-Office apps and Visual Studio) are being called from a multi-threaded application (such as the PlanetPress Workflow tools). The error occurs randomly and is due to a timing problem in those applications. The only recommendation that can be made to remedy the situation is to... try again later! More information can be found on the MSDN web site, in particular on this page:
"http://msdn.microsoft.com/en-us/library/ms228772(VS.80).aspx"
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Technical Product Manager
I don't want to achieve immortality through my work; I want to achieve immortality through not dying - Woody Allen