Computer not turning on?

Ok i press on and it does exactly this: Its vista new laptop compaq presario

Black screen
takes longer than usual on the windows loader
black screen for like 15 seconds
black screen forever

RESTART PC AGAIN THIS HAPPENS

black screen
"windows error recovery"
"windows failed to start. a recent hardware or software change might be the cause. if windows files have been damaged or configured incorrectly, startup repair can help diagnose and fix the problem. if power was interrupted during startup, choose start windows normally
(use the arrow keys to highlight your choice.)

Launch startup repair (reccomended)
Start windows normally"

i click launch start up repair
black screen
Windows is loading files… (white bar under text)
black screen
windows loader microsoft corp
goes to a really old windows style computer with the blue background
stat up repair cannot repair the computer automatically.

iclick view advanced options for system recovery and support
i try all the things in there to help recover computer, none work. all fail, i go back and click view diagnostic and repair details

just shows basic info of my pc like 10 pages worth i click finish, comp turns off.
WTF DO I DO. its been like this like a week.

Hi,
My computer was fine just the other day, but i started it up today and now it wont boot up! I get an error message ‘Windows failed to start. A recent hardware or software change might be the cause.
File : CLASSPNP.SYS
Status : 0xc0000221
Info : windows failed to start because a required file is missing, or corrupt.

I put my vista setup disc in, i ran ALL the things it told me to (system restore, windows memory diagnostic, system repair, command prompt) but still they all fail.
I dont want to lose ANY files, because i have been doing lots of work lately on the pc and saved lots of important documents, is there a way i can reinstall vista without losing any of my important work?

I tried turning on my laptop and it takes me to a screen which says "Windows failed to start. A recent hardware or software change might be the cause." It then gives me two options, which are "Launch Startup Repair" and "Start Windows Normally." I have tried using both, but either choice makes my computer restart and takes me to the same screen. Alt+Ctrl+Del restarts my computer as well. Escape shuts of the timer to automatic selection. I have tried running both the recovery CD and the support CD, and neither works because Windows is not operating. Do you have any suggestions as to what I should do?
I cannot give the computer any commands via mouse, and it will not respond to any keyboard commands either.

I have a gateway laptop and whenever I turn in on, it wont go to the log in screen. I says :

Windows failed to start. A recent hardware or software change might be the cause. then there are 2 options Launch start up repair or start windows normally. When i clicked start windows normally, the green bar thing loads for like 5 minutes, then it just goes black. When I tried Launch start up repair, the results showed 1 root cause. It says system volume on disk is corrupt
repair action: file system repair (chkdsk)
result: completed successfully error code 0x0

Can anyone please help? Thanks in advance

My brother built a new computer based around a new processor and motherboard, (intel Quad-core Q6600 and Asus P5E), along with a new case so it would be compatible(Antec 900). After transferring over these new parts along with the necessary older parts the computer works fine except for one problem. Everything powers on, the computer gets past BIOS and then goes to boot windows but instead he gets:

"Windows Error Recovery"
Windows failed to start. A recent hardware or software change might be the cause.

If windows files have been damaged or configured incorrectly start up repair can help diagnose and fix the problem. if power was interrupted during startup choose start windows normally.

Launch startup repair(reccomended)
Start windows normally

Whenever he starts windows normally he gets the blue screen of death and an instant restart. If he launches repair it goes to a loading bar that completes in about 5 seconds then just sits at 100% and does nothing.
P.S.
We do not have a copy of windows vista, it came installed on the computer and we never recieved an actual copy.
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To Tina G
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He cannot get to the actual desktop to do any of that from, windows will not launch.