As stated in the MS KB Q261218 Windows 2000 does not pass MSL_TEST. I got the prereleased version of W2K-SP 1 and changed the corresponding registry key. But this results in a TIME_WAIT state of 241 instead of 1 - which it was before.
Answer by Amnon Horowitz:
You need to set both StrictTimeWaitSeqCheck to 1 and TcpTimeWaitDelay to 60 under tcpip/parameters. Right now, it looks like you didn't set TcpTimeWaitDelay and you are running with the default of 4 minutes (240)