Computer won't re-boot after shutdown

[mendopaul]

I can get my computer booted only after clearing the bios with the jumper and renewing the BOS settings. Then when it is powered down it won't complete a bootup. It will POST and complete memory test but then won't seek the OS to boot Win 7. This has just started a few days after upgrading Vista to Win 7 Home Premium but I'm suspecting hardware problems rather than software.........but I'm at a loss as to what to do. Help please! This computer is 4 years old and had rarely had problems of any kind.

 

[mendopaul]

System Specs

Forgot to include system: Home Built: ASUS MB P5B deluxe, Intel dual Core E6850 at 2.6ghz; 2gb of Ram; ASUS Geforce 8600GT; WD Raptor 74gb; HD's at 500gb, 320gb, 640gb; Thermaltake 650watt Modular PS; Antec Sonata III; Sound Blaster Audigy SE; Happague Wintv. Machine is just over 4 years old with no significant problems in the past. Have just upgraded a few days ago to Win 7 Home Premium.

 

[mendopaul]

Post OK but won't boot!

I thought I'd better clarify my problem title for clarity. What could be corrupting my Bios so that I have to clear it to get it to boot?