Confused about preg test!

A friend of mine was about 5 days late... she did a test, waited a few minutes and it was neg. She put it down, relieved, and forgot about it.
A few hours later she went back and found a pos line had appeared too.
The next morning she did another test.... waited and waited.... neg.
Left that one for a few hours and came back..... AGAIN a pos line had appeared.
She was pretty sure the tests were accurate if read between 3-5 minutes. But she rang her doc just to check, and they said a pos result can take from 2 minutes to 2 hours to appear.
What the! Never heard of that.
She's desperately trying to get in to the doctor to get a blood test, but no luck so far.
What do you think? Should she take it as a POS??
Anyone else experience this????

Hmmm...I've always thought after 10 mins you should disregard the result and test again.
I guess I would take it as a negative but get a blood test just to be sure.

Can she try a few different brands?