From personal experience from connecting SUN-servers to cabletron switches, I can tell that there are a lot of incompatibilities in the autosensing-protocols from various hardware-vendors.
Especially the full-duplex negotiation doesn't work properly. The SUN starts the negotiation-sequence, which is unanswered, causing the SUN to retry endlessly.
As the protocol runs on a lower level than IP, all other IP-traffic will suffer from high collision-rates and network-errors. The solution ( for SUN's ) is to switch auto-negotiation off completely.

Frank van Gestel