[pptp-server] Error 650

[robert]

I'm trying to connect to a Linux PPTPD server from a windows 95 machine.  I 
get an Error 650 every time.  Three other windows clients (including one that 
uses the same DSL provider as I do) can connect no problem.

This says it is not the server that is the problem.  The fact one of the 
other clients uses the same ISP tells me that ISP filtering is probably not 
the problem.

One of the howto's mentions this could be a firewall problem (not passing GRE 
packets).  However, the client that can't connect is directly connected to 
the internet (as least during tests).  No firewall, no NAT.  Therefore, I 
don't think that is the problem.

The setup, BTW, is pptpd 1.1.2, pppd 2.4.0, kernel 2.4.1.

Anyone have any ideas?