How am I to troubleshoot this. This message is from a 3500XL Switch ( one among the cascade configuration)

We have 8 switches in cascade (Half Duplex Gigastack) . Lets say Switches 1-8. A fibre from our main building land at Switch 1. There is an uplink to another building from Switch 3.  

[3500XL    ]
[3500XL    ]
[3500XL    ]
[3500XL    ]
[3500XL    ] gig to another building
[3500XL    ]
[3500XL    ] <- fibre from manin building

1)We have couple of hubs connect to various ports on these switches
2)I get this error message  %SW_MATM-4-MACFLAP_NOTIF: Host 0201.0000.0000 in vlan 2 is flapping between port Gi0/1 and port Gi0/2
3) I also have lots of collision on Switch 1's exit port to Switch 2 ( Do I need to post sh in gig 0/1 ?)
4) What will be causing these collisions? How can I find the culprit(s)?
5)We will be replacing the hub with 8 port switches soon
6)We have vlans running for data/voice/management
7)Yes, its trunked and sort.

Is there a better way to reconfigure this Star ? But then there will have to be a purchase.

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if each switch is connected to the next one with 100mbps, then you can reconnect them in star topology with 3550 as an aggregator.
collisions are caused by hubs - change them and there will be no collisions at all.
0201.0000.0000  belongs to microsoft load balancing service.
i suppose you have one behind gi0/1 and second behind gi0/2 ports

jkdasAuthor Commented:
100mbps would be slower right since now each are connected via gig ports.

For some reason 0201... vanished! Found that there are 2 hubs causing collisions.

jkdasAuthor Commented:
Should I give the connection given in blue? Now its disconnected as we had too much collision; ie,without removing hubs.

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this blue line will cause loop within your network.
if you have spanning tree protocol set up properly this link will be used as backup.
but if you have no spanning tree set up, then loopguard will put one of the gig ports to err-disabled state.
so until you need redundancy there is no need in this blue cable
jkdasAuthor Commented:
I do have spanning tree running.

Another doubt I have, would it be fine if I connect it back as I already have collision at some point due to hub ( which will be replaced shortly). Would these collisions be amplified ?
no, you see spanning tree will disable the whole port unless there is loop.
collisions do not affect this behaviour

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Switches / Hubs

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