Steps to recreate
http://dl.dropbox.com/u/17111233/client3-network.sve
1. Go to Longford railway station
2. Use track removal tool and drag from 140,334 to 141,334, which should include an end of choose signal.
3. Game should crash instantly upon completing the remove command.
Oddly, using destroy/remove tool to delete the end of choose signal does not result in a crash.
Thank you for the report - I think that I have managed to find/fix this on my 10.x branch. Most helpful.