PC not booting

Hello,
I am using hp lap top (dv6-1334us Entertainment note book) since last two months it is not booting at the required speed.
when turned "on" in the first instance the logo of hp is lighting up. it takes half an hour and some times even more and later a small dash blinks on the left hand top corner of the screen in black. here also it takes hours together before it is get booted OR some times not booted also till I turn off in distress.
what would be the cause ?
note: the system is re configures recently 4 months back. for two months it worked as usual and later developed this problem.
before re configuring also the above problem persisted. hence it was got re configured.