VNAV PATH to VNAV SPD
On the NG with FMC version 10.1 if you get too high...500ft above your path on descend the pitch mode goes to VNAV SPD from VNAV PATH and the throttle mode changes from ARM to N1. So on the FMA the display will be N1-LNAV-VNAV SPD not the normal ARM-LNAV-VNAV PATH.