New
#21
Why is everyone worried about partitions, etc. when the problem has to do with the BIOS? If the BIOS isn't seeing the drive during POST, then all that other stuff isn't relevant.
How old is this thing? Because this is intermittent, you ought to see if there are BIOS settings that are either corrupted or improperly set due to low battery voltage.
I suggest that before you go spinning your wheels too much more, you remove the 2032 battery and let the BIOS settings clear themselves. While you're waiting for that to happen, measure the voltage on the battery and replace it if it's under 3.00VDC. After you know that the battery is good, and the settings have completely cleared, then re-set everything in BIOS and try it again.