Hey,
I found out that the batman-exp daemon goes crazy when its internal life-time
variable overflows. This will happen after 49 days, 17 hours, 2 minutes, and
48 seconds (which corresponds to 2^32 milliseconds). Unfortunately, its
behavior afterwards can be anything between hanging around and doing nothing
and an endless loop of sending packets. The problem is fixed with revision
972.
If you are running batman-exp I strongly suggest to update.
ciao,
axel