I have a 3500xl stack connected by Gigastacks. The first switch and last switch in the stack are connected with the giastack cable as well.
The gigastack interface on the last switch in the stack is Green/Green but the gigastack interface on the first switch is Green/Red and ideas?
I have attached a screen shot to explain it a little better
I have seen similar behavior with gigastacks when you connect them redundantly forming a loop.
I think the behaviour is similar to spanning tree where the blocked gigastack port shows orange.
If you remove any one of the gigastack connections and break the loop, you should see the light coming green
HTH, rate if it does