I have problem booting my comp.
Because it always looks for the missing OS, i try several times using a cd to reboot it, but doesn't work either.
Please give some tips
There are some possibilities to be considered when encountering  such issue. Initial Example,  Hard Disk Drive failure due to bad sectors. Bad sectors on your hard drive affects it’s consistency. In some occasions, you may think everything is running perfectly when the Hard Disk Drive is detected by the CMOS.
 When your Hard Disk Drive is detected by the CMOS but fails to continue to run Windows it’s a proof that your system has hardware issue. As an initial troubleshooting step, turn your system off and try to reset data cable by unplugging it from the data port and plugged it back in.
This is to identify if date cable is working. Â When this fails, Â try using a new data cable port.
