In Solaris10 I changed NIC drivers from bge0 to bcme0 via package install with no problems. I disassociated bge and after a reboot and some hostname changes new driver loaded OK.
Now trying to rollback after unplumb and downing bcme0 I cannot plumb bge0
ifconfig bge0 plumb
ifconfig: cannot open link "bge0": DLPI link does not exist
Now trying to rollback after unplumb and downing bcme0 I cannot plumb bge0
ifconfig bge0 plumb
ifconfig: cannot open link "bge0": DLPI link does not exist