[Pierre-Marie Baty]

erm, several reasons to crash here...

Before doing ANYTHING with an edict_t pointer, test it with FNullEnt(). From my own experience a null pointer test is never enough. FNullEnt() actually makes sure the address the pointer points to is really the address of a registered, active, entity.

You have to do this for:
pPlayer->pev->groundentity (can be null)
pEntity->pev->owner (can be null too: what if the owner dies ?)

Also you can save yourself the cost of the TraceLine: if the player is standing on the ground, his flags will be FL_ONGROUND (standing completely, i.e. origin is above) or FL_PARTIALGROUND (standing partially, one foot aside but one foot on it. Here the TraceLine would fail)
And pev->groundentity is reliable, when it is not NULL. If (ground flags && pev->groundentity && groundentity is hive) then you can inflict your player some damage.