I hope somebody can explain the following IDA behaviour and suggest some solution.

This refers to IDA 6.1 running under Win7 x64. (No problems at all in 32-bit).
When I trace some 64-bit program (with lots of modules), most of the time I get one of the following error popups:

"oops! internal error 40208"


"irs_recv: The wait operation timed out."

If I use IDA 5.5 x64 instead, the message becomes:

"rpc event protocol error"

This is clearly a communication timeout but I have no idea where it comes from.
Only topic on it I found, pointed to armlinux_stub.plw which shouldn't apply to my case.
Also the title of an unreachable link refers to rpc_debmod.cpp which again should not apply.

Nothing in the system's event log and nothing obvious in IDA's log.
No blocking by the firewall and no difference if I disable the network controller.

It could relate to the module I'm modifying of course (but why IDA crashes?) but again I don't see anything.
No TLC in the module, I break when it loads and while I just look at it, I get the comms error.
The fact that it doesn't happen all the time, complicates it a bit.

I checked all the .NET Frameworks in the system and they are clean and properly registered.

What else could I be missing?

Thanks in advance for any pointers.