client close after sending password crypto seed

pretty much as title says, client close after sending password seed
i've done some debugging, packet is correct with right structure (len 8, type 1059, random seed on offset 4)
im using a public loader on patch 5856 with custom source
loader is pretty straight forward, i did try to debug client with olly but nothing obvious, so was asking if there is something i duno before i digging deeper for couple of hrs figuring it out

Check the debug folder for crash dumps (not all that helpful) and also client logs. You might get some insight about what happened from the logs, but at first glance it sounds like a cryptography issue.