http://jan.blocknet.net/ForgeModLoader-server-0-new.log
I looked at the new log file and there was sth about an ender bee and the dragon egg
at forestry.apiculture.FlowerProviderEnd.isAcceptedFlower(FlowerProviderEnd.java:18)
so i removed the ender bee i had in an alveary in this world and now it seems to work again
the server did not crash when i was in a different age because the area with the alveary was the only one which was not chunkloaded...