ShadowGriZZly is right. The client used a fixed 32 parts buffer to store the ","-separated values, and the new COMBATANT_INFO line had too many commas for it to handle. Can you check if the new client works for you? You can see the version in Help -> About, version 7001 (classic) and 7002 (bnet-login) have the fix for this issue.
I don't read the forums as often as I should, if you need help with a high priority issue, please send me an email at email@example.com.
Fixed the fix. The client buffer was resized, but forgot the one on the server.