Hello!

Technical explanation: Late Collision is a type of collision found in the CSMA/CD protocol standard. If a collision error occurs after the first 512 bit times of data are transmitted, a late collision occurred.

In your particular case you see this messages because you have a duplex error on the interface, exceeded cable length, incorrect cabling, bad NIC.

If you are connected through console than these messages are to be showed, but if you are connected through vty lines (telnet, ssh) you have there a "terminal monitor" command that force these messages to appear on your screen. To force messages not to appear (on vty lines connection) issue "term no monitor". But this will not make your problem go away.

Check the possible causes that I mentioned above to solve the problem.

Good luck!

Cheers,

Calin