PC will not run

I have a Compaq Presario that starts and runs for aprox. fifteen seconds then
quits. I checked all the connections took the cover off gave it a good dusting but it still will only run for fifteen seconds or so, any help will be greatly appreciated?

Thank you,
Tee

 

I press the start button, the PC starts no images or error messages on screen
runs for a few seconds then quits, I restart the same thing happens again and again, I let it rest overnight, It started the next morning ran fine for several hours, I was able to receive e-mail and surf the net. Several programs posted error messages .....unable to end program....I tried ending them with taskmaster
and they closed but the machine shut down and will not run again....

 

I press the start button, the PC starts no images or error messages on screen
runs for a few seconds then quits, I restart the same thing happens again and again, I let it rest overnight, It started the next morning ran fine for several hours, I was able to receive e-mail and surf the net. Several programs posted error messages .....unable to end program....I tried ending them with taskmaster
and they closed but the machine shut down and will not run again....

No I cannot get into safe mode but will try again.

 

No cannot access the PC at all it will start but nothing appears on screen,
I tried pressing down the F keys that respond to safe mode and it just starts up for a few seconds then shuts down. I even tried to boot from a floppy but it does the same thing It fires up briefly and then shuts off. I tapped the start button from inside the case and it did start this morning and ran fine for several hours, but when I tried to end a few running programs I received the message program not responding I hit ctr and delete and tried to end the program but it still would not respond and then the pc shut down and will not run at all.

 

I removed the hard drive gave the inside a good blow out, stripped down to just a monitor mouse and keyboard. Put in an emergency 3.5 floppy and the machine purrs like a kitten. With the face plate off the machine I dilly dallied with the start button, heard a little click. I shut the system down mutiple times and it has restarted every time since. I do not smell any peculiar odors coming from the power supply. I resinstalled the hard drive and backed up all
the information that is important to me. I'll continue using it and if it performs with out that glitch.....I'll reattach my cable modem.....this is an old machine
I'm using now it only has 256 memory.....but it is reliable for surfing the net
I put my firewall and virus protection on it .... thanks for your tips they got
me curious and I delved into the machine and well I'll just keep my fingers crossed, and pray it stays up. If not I got this old HP pavillion to keep me on line til Vista comes out and I'll purchase a new one. Once again thanks

 

removed the hard drive gave the inside a good blow out, stripped down to just a monitor mouse and keyboard. Put in an emergency 3.5 floppy and the machine purrs like a kitten. With the face plate off the machine I dilly dallied with the start button, heard a little click. I shut the system down mutiple times and it has restarted every time since. I do not smell any peculiar odors coming from the power supply. I resinstalled the hard drive and backed up all
the information that is important to me. I'll continue using it and if it performs with out that glitch.....I'll reattach my cable modem.....this is an old machine
I'm using now it only has 256 memory.....but it is reliable for surfing the net
I put my firewall and virus protection on it .... thanks for your tips they got
me curious and I delved into the machine and well I'll just keep my fingers crossed, and pray it stays up. If not I got this old HP pavillion to keep me on line til Vista comes out and I'll purchase a new one. Once again thanks