windows xp won't start!!!

i got major problems. soone day i finish using my computer, didn't do anything special, just surfed the internet, and didn't add any new hardware or do any updating. so i shut down my computer normally and went to bed. then next day i go to turn on my computer and its goes through the bios info and some other system info and then goes to thewindows splash screen with the logo and the status bar that keeps rolling. essentially that is my problem. it gets to that point and the status bar keeps moving however the computer does nothing. seems like it just gets stuck but the status bars keeps moving. i have tried so many things such as system restore, booting in safe mode and running spyware sweeps and virus sweeps, i ran chkdsk cause i thought it may be a problem with the hard drive, i tried using a bootable disk made from another computer with windows xp and that did absolutely nothin, it just ept goin in a continuos loop where it would attempt to start using the disk then it would shut down and ry again, i also tried removing some hardware like video cards and tv tuners to see if that was the problem, and so far i've gotten no where. basically i'm stuck and its driving me insane cause i can't figure it out. just so u know i'm running windows xp pro with service pack 2, i have an asus A8N SLI mobo, an amd dual core processor, a maxtor 300 GB drive, a GeForce 6600, 1 GB of ram, and a v-stream tv tuner. if anyone could get at me with any ideas with what the problem is that would be awesome. thanks for the help. if u have any questions about my comp info just ask and i'll let u know. thanks again.