Hmmm... well, I had a positive HPT, then I got a neg HPT at the Dr's, then another 2 postives HPT's at home, then a neg at the hospital, but my hCG levels kept increasing, so it looked as though I was pregnant... in the end I miscarried, but it was after loads of BT's and ultrasounds. So perhaps she is going through something similar... but the fake HPT's were a bit bizarre.
I hope everything is going to turn out ok.