This switch has been operational for about 5 years. There were some errors, but I cleared the counters and I don't see any errors for the last 20 minutes.
Find out what model then do a search in CCO for the model you have and what the LEDS mean on the front . I never use them other than to make sure it has power anyway .
What is the color of the LED? Green or amber/red? Look at the status light (over on the left). Is it Green or Amber/Red?
Model does make alot of difference. The 2900/3500XL switch port LED goes red when line errors occur (such as duplex or speed mismatch). If amber/red is constantly on (as compared to occassional blinking), it means that the port(s) have failed (Loopback test failure) or spanning-tree port blocking.
For other models after this generation of switches, amber/red lights constantly on on the switch means either ports are error-disable, ports down due to Trunking mismatch, duplex/speed mismatch, etc, or spanning-tree port blocking.
It also depends in what mode it is in on front . There is usually a mode button on the left that you you push and it will cycle thru like utilization and status and maybe one other state. For like a 2950 take a look here.