Vector death spiral

The vector seems to fly OK until I slow it down too much or let it get out of shape too much.It then goes into an out of control death spiral which is impossible to pull out of.This results in a nose first ground encounter of the worst kind.
Is this normal for this model?I have tried different control throws but nothing seems to help.
Any suggestions,other than burning it?

My experience is similar,
random rapid rolling to one side then plunging into a dive (tip stall). Suggestions seem to be move the CG forward, keeping the speed up in turns and mix some rudder (how much??) into the ailerons. I found this plane to be sluggish on the HK recommended 2 cell battery, but much much better on a 3 cell (as recommended on box). Some have said that the supplied ESC has no low voltage cut-off, but I wouldn't know as I am yet to finish a pack! Its definitely has a rapid roll rate on full throws, however, when I try and pull a loop it tends to roll to one side not sure what thats about. Not sure what to do with this one.

LC