Okay, I found from websearching that getting killed in Caergate loses RP and EXP, so I guess I'd just better stay out of there. I was hanging around there trying to get some kind of angle on PvP, but if practising (i.e. getting killed a lot) costs me points, that's too much of a cost.
As I said above, i'm new to this, and have been trying (and failing) to grasp how other players appear so vastly more powerful than me. My girl is a level 25 Punisher, but it seems as soon as an RG spots me, I may as well just start writing funeral invitations. It's normally over in like 3 seconds of watching her go "uh uh uh", usually unable to even get a return shot off, in a blaze of graphics, before the fally-over-monochrome bit. It's like every mech has a special "kill Labooba" skill.
So anyway, that'll be the cause then