Connecting 3 switches to a fourth switch, each with its own crossover cable shuts down ports

This is probably a very basic question but I need to ask it anyway
since there is no easy way to test it while everyone is on the
network. I have (3) 3com switches, all are connected via a proprietary
backplane cable called a matrix cable whis is sort of like a crossover
cable. I added a fourth switch, a Cisco catalyst, and decided to plug
each 3com into the Cisco switch using three crossover cables, one
cable for each 3com, connected to the Cisco. Later I would connect the
Cisco to a trunk. After plugging in the three xover cables I noticed
only one port was active, and if I unplugged the active port, one of
the other two ports became active. Is this spannig tree? was it doing
this to prevent a loop? Will this config work once I remove the matrix/
backplane cable?

thanks
NH

 

Yes.

Yes, because you made loops. The stack cable makes the 3 behave as one.

It works now.

But, yes it will still work when you unstack them as well.

 

Thanks!