There are several hist on this on Google. This is MS error so I would suggest to open this with MS support. Before you do that you wish to check any additional messages in event logs. FYI, error is generated during call to this function http://msdn2.microsoft.com/en-us/library/ms878545.aspx and that fails on EXCH side as it seems.

Also, if you paid more attention on some search hists you would on first result page you would find following:
http://support.microsoft.com/kb/935634/

There is probably more, but MS support is the way to go now.