computers hang

Has anybody seen this? Are corporate MIS replicated Active directory out to are NT 4 bdc’s/pdc’s. Now we have systems hanging on either : preparing network connection or applying computer settings. If we disconect the network cable the machines bootfine. Randomly our 2k machines are becoming AD aware and start showing these symptoms. Are corporate MIS pukes are worthless. We have tried numerous things to resolve but are still stumped. Any thoughts?