Switches have their place but they are not the "cure all" that current marketing literature makes them out to be.
YES - switched networks have collisions. Take the example of a small network with one server that also serves as a gateway. The switch port with the server/GW is in essence a "shared" segment with all of the client PC's. Unless there is peer-to-peer network traffic a single server/GW network will see NO improvement when changing from a hub to a switch.
On a managed hub (where you can see such things) you will see several statistics for collisions. Nortel switches commonly report Collisions, Single Collisions, Multiple Collisions, Excessive Collisions and Late Collisions as discrete values for each port.
It does not matter how many lanes a superhighway has if everybody is going to the same BBQ joint, there will be a traffic jam...
In my opinion there are WAY too many switches being installed. Switches (especially cheap ones) have their own set of problems and add complexity to a network. I have never had to "reboot" a hub but I have seen networks malfunction when a switch's tables get horked and need to be reset. Spambots and other network "evildoers" are much easier to find on a hub network than a switched one.
Appropriate use of technology should be the design goal. Ethernet is a shared media and collisions are a part of that design. Unless collisions reach unacceptable levels there is no need to worry about it or install switches.
That is my usual "switch" rant. As to the original question my guess is either what Servamatic said or noise on pin 1 (unbalanced due to pin 2 open) causing problems on the switch.
