My 24 port dlink switch has been misbehaving for two months now ,it looses connectivity to a pc can sometimes partially which means it can receive mails and not send for only this one pc .....when you change ports it works fine
Is it just one port that has problems or does it lose connection later on on different ports? From your description it sounds like just one port is not working. Tape over it and don't use it. Ports can go bad.