NO Os found after restart and after power failure.

[dlvsm]

I have a Hp Pavilion PC-D5000T that I bought off e-bay about year ago. Said it was refurbished but new. Has all kinds of extras like 6 gig ram, upgraded video card, tv tuner, blue ray player ect.. Has worked fine until now. 2 weeks ago the computer was restarted and when rebooting said no os found. I did not receive any disc's with the system new but was not worried as i assumed it had a partitioned section of the hard drive for recovery. This is not the case for this issue but I have another recovery disk from another computer for Vista so used this to reboot the computer. This was fine for about a week and half and i had restarted the computer a few times since from updates from Vista ect but last night the power went out and when i turned the computer on again I received the same issue. I did a diagnostic and all came bask OK but I did get the error code biohd-4 error report as a corrupt to bad boot path. Used the same disc as before to reboot the computer and again it is working fine but can anyone tell me what the issue could be? I called HP support and they claim it is a virus... I am not buying this as if I completely wipe the hard drive and reinstall vista this should take care of itself so even if AVG did not catch this virus it would be gone now. Plus they wanted $40 to fix it but the guy could not properly explain to me how this could be, I googled this error code and found some other thetas that reference this error code but nothing that accurately explains my issue. Anyone have any ideas or help is appreciated.

DLVSM