Vista won't boot up

I'm running Vista Home Premium 32bit on an emachines T5254.

Two weeks ago the computer shut down during a time when it was normally left on. On restarting the "Computer did not shut down properly screen" came up with the "Start normally" and "Startup repair" options. I chose startup repair and the computer immediately shut down. I restarted and at the same screen chose to start normally. The system booted up normally and seemed fine.

The next day the same thing happened except this time it took 4 tries using the start normally option before it would boot up. The other times it would shut down immediately after selecting the startup option. At this time I tried a system restore to before the most recent updates. The restore began and then stopped with the message "System restore has encountered a problem. No changes were made to your computer." I tried other restore points and got the same result. Shortly after trying for the 4th time, the computer shut down.

After restarting multiple times again with no luck, I decided to boot from the OS disc. The "loading files" bar appeared at the bottom and as soon as it got all the way across, the computer shut down. Tried multiple times and same result.

Tried to boot up in Safe Mode by pressing F8 and no matter what option is selected, the computer shuts down immediately after selection.

For the first week I tried these options over and over again. I was sometimes able to get the computer to boot up when selecting the start normally option, but this was sporadic and each time seemed to last a shorter amount of time before the system would shut down again.

As of late last week, I cannot even get the system to boot at all no matter what option is chosen. Over the weekend I attempted to boot Knoppix directly from a disc. It went through the loading files part and then the system shut down again.

I've visually inspected the motherboard and see nothing obvious.

Any suggestions? At least a hardware or software determination that can be made from everything I've tried?

Welcome
Works sporadically, but not with many tries. hmmmm. Overheating is a good possiblity. Open her up and clean out that dust.. Buy some canned air.

Already cleaned it out really well. Didn't change anything. Fan is working fine.

Also, the computer can stay off overnight and then upon trying to start up it does the same thing. Doesn't seem like an overheating issue.

Might not be overheating, but most likely hardware. Does not work in safe mode is not good.
Here is our post for BSOD error 124, which is hardware. Code 124 does not indicate where it is though
Stop 0x124 - what it means and what to try - Windows 7 Forums

Thanks for your help. I'll borrow some hardware from a friend and see if I can pinpoint the problem.

I wish you luck and you can come back with questions.

i have the exact same problem with my computer and am wondering if you have found out any solutions

philly, my issue was hardware. Replaced the motherboard and took care of the problem.