I cannot comment on Metroworks, but I have used the CAN on the coldfire board. I used it in a loopback configuration sending packets back and forth between the two can ports. This was without any OS.
I found a note in the freescale errata document (section 5.1).
http://www.freescale.com/...errata/MCF5485DE.pdf
Could this have anything to do with what you are seeing??
Eric N