I was helping my freind fix his freind CD drive. So we opened the case the we replace the cd drive.But first we accidently took out the hardrive. Then after that we put them all back in carefully.Then things started to go wrong. Everytime we booted up the system a black screen came and it said press F2 to goto setup or F11 to boot from a disk or something i cant remember. So we tried installin Windows XP again but it said it could not detect hard drive. So we decide to put the CD drive on Slave and leave the hard drive on its normal settings.Then it all lit up and now it wont turn back on. Any help??