Not sure if this is a Forestry issue or Railcraft but wanted to try and help with the bug discoveries so setup this account to report back. In this particular instance Bio-Fuel was entering Iron Tank via Thermal Expansion Liquiduct from Forestry Still. Have not tried with other transport mediums. Have to roll back server when it happens as unable to log in (client just crashes as I assume it loads the chunk on logon with iron tank/Bio-Fuel in and then crashes).

Client crash error : https://dl.dropboxusercontent.com/u/5708700/crash-2013-04-29_14.49.36-client.txt

Let me know if there is any more info required or want me to test a different setup.

Forestry bug.

Thanks, I have posted the client error on Sir Sengir's bug report as well. Appreciate looking into it and good luck with the development!