Problem with VPN and RPC

Hi,
I’m having an issue with VPN.
Sometime, when I’m connecting (PPTP, cisco) my computer hangs up, and RPC crash, asking me to reboot.

Here is what I got in the even viewer:

The COM+ Event System detected a bad return code during its internal processing. HRESULT was 800706BE from line 44

The Remote Procedure Call (RPC) service terminated unexpectedly. It has done this 1 time(s). The following corrective action will be taken in 120000 milliseconds: Reboot the machine.

I’ve tried different things to solve the problems, but it still randomly crash.

I’ve already done a virus/malware etc scan, and everything was fine for that.

Thanks for your help!