first do a show post to see if you passed the last power on.
there are some basics you can run but i'd be interested in a ping through a loopback with large-sized numerous packets. the loopback is to keep it limited within the asic primarily...
now do a show controllers ethernet-controller fa0/1 (the test interface).
i don't remember right now how many asics are in the 2900's (1 master, 1/4 ports, ...?) but if there were more than one it'd make sense to span asics...
you can also turn on select debugs like for ethernet-interface.
also, you didn't mention the switch model but you could take an l3 rev of 2948g and check the ios bug matrix (just a thought).
did you do an update to eliminate a bad image?
i hope this little rant helps in some way. have to run...
matthew