PB with my OP's recognition

Hi,

I would like to know if anyone else has the same problem as me and if you guys can help me out. Sometimes, when I turn on my laptop it just says "operating system not found" and I have to turn the computer off and start again. Sometimes, it even does it again 3 or 4 times before it actually starts normally. I reinstalled my operating system but it keeps on doing this. Do you think it's more of a hardware problem? thanx in advance for your help....