Help: The original OS is winxp-professional, maybe i change some setup from "BIOS" or "system configuration utility" and when i restart pc, it shows black screen and this information: "Error loading operating system". even i am not able to go in "safe mode". because this is a new computer, so i reinstall with winxp-home edition by cd-rom and format hard-disk already. but two times after, the problem is still in. Thanks for any help.