[j-nsp] What does AS path attribute problem mean?

[Markus]

All of a sudden without changing anything in the config I'm getting the 
following on a M7i running 8.0R2.8:

rpd[3019]: bgp_read_v4_update: NOTIFICATION sent to 89.146.xx.49 
(External AS xxxx): code 3 (Update Message Error) subcode 11 (AS path 
attribute problem)

The other end (Cisco) is getting:

%BGP-3-NOTIFICATION: received from neighbor 89.146.xx.50 3/11 (invalid 
or corrupt AS path) 0 bytes

This is causing the BGP session to flap. It happens at arbitrary 
intervals, sometimes once a minute, sometimes just once in an hour. CFEB 
and RE CPU are at steady 100% when it happens.

What can I do about this and what could be the cause? Help! :)

Thanks!
Markus