Upon boot my Emachine says "Operating system not found." I have tried to change the primary master in the bios because it says [none], by pushing +/- but it just beeps at me. Tried loading windows again and it seemed to go smoothly. Restart just goes back to "Operatings System Not Found"

Test the hard disk; Disk Diagnostic Tools, Major Manufacturers It's a good day when you learn something

Thank you, how can I test it if it is not recognized by any machine?

Your two posts seem to suggest slightly different events... Initially you day no OS found; then in the second the drive itself is not there? These are not necessarily the same event/issue; although a no HD present can obviously produce a no OS result too... Meanwhile - power off system; remove mains from the system entirely - as in remove the power lead... Open the case; reseat all connectors for the drive; ribbon at both ends, and the power connector. And whilst in there.. check all other plug connections on the MoBo... Then restore power and see what happens? If drive spins up (and you will usually hear it) and the drive access light (ought to) comes on... then at least you'll know it's there. Also if you can access the bios settings... ensure/check the drive is detected there; use the auto-detect mode to enter its settings. Then using the util suggested by Dan you can check drive integrity.

http://support.microsoft.com/defaul... "Operating System Not Found" or "Missing operating system" error message when you start your Windows XP-based computer

"..how can I test it if it is not recognized by any machine?" Many of these tools bypass the bios and "talk" directly to the hard disks logic board. It's a good day when you learn something