My system specs are Windows Media center edition SP2 DELL XPS AMD Athlon 64*2 Dual 1.9GHZ and 1.00GB RAM My computer was showing the blue screen for last couple of days after I installed Oracle db and had problems and had to install multiple copies and deleted the old copies and kept only one database. I had clened up registry related to Oracle software. It worked good for few days and then started showing the blue screen. I did defragmentation. I did chkdsk /f and /r both but still no improvement and I was thinking to restore to original time but could not do it and now computer is not booting . The monitor also does not turn up (stays yellow light)so I can't go to safe mode now. Computer powers up well and I can hear fan. I don't have boot CD. As this computer was built up by someone taking some parts out of my original DELL computer, I notice there is option for CD and no diskette drive. Please help. I saw the sites like bootdisk.com and ultimatebootdisk but don't know which one should I go for and what should be step by step procedure. I am not comfortable with trobleshooting with computer so want help . Thanks. mai_sha edited I just found the paper where I wrote the message one time after one of the BSODs and it says Faulty or mismatched memory STOP: 0*0000007F (0*00000000, 0*00000000, 0*00000000, 0*00000000) May be whole problem started because I modified the registry but before that i was getting some other error ( ithink it was isqlplussvc.exe) which made me to delete multiple copies of databases and hence all the problem. Also monitor is in power save mode and looks like it has got stuck in that mode. Please help what should I do. Thanks.