You are encountering the famous err-disable port problem.
The port could get into this state due to the various reasons. So check the root-cause as described in the following document.
You can also use the "set option errport enable" command to fix this problem temporariy. But read the "Causes of err-disable" and "recovery from err-disable" sections of this beautiful document before choosing this fix.
http://www.cisco.com/en/US/tech/tk389/tk214/technologies_tech_note09186a0080093dcb.shtml