I need to change the speed to 100 in the 6500 switch port, when I do this, the interface become UP.
Have you seen this before?
Yes I do. ALL the time.
This is caused by a fault in your cable. Pair D of your cable controls GigabitEthernet and it could be the fault. There's one way of testing and it would mean running a TDR from the 6500. Here are the process:
1. Command: test cable tdr int Gi4/36;
2. Wait for 61 seconds (Yes, it takes THAT long when dealing with 4500/6500 line cards);