BIOS not detecting devices

[XJET]

I have an Aspire 3050 running XP, which when booting, gives the message 'Operating System Not Found'. I have checked the BIOS and neither the hard drive nor the optical drive are detected, the USB ports are also inactive, the hard drive works fine in another machine.

Memory check is good and there are no beeps on POST. Any advice on possible causes or further checks would be greatly appreciated.

 

[treetops]

Zoom in on this, it helped me eliminate a lot of potential problem I might have been having
http://www.fonerbooks.com/poster.pdf

 

[XJET]

Thanks treetops. Since posting the query I have investigated further and found that by applying pressure to the CPU whilst booting, start-up is successful. There must therefore be a fault on the board in that area,