Try disconnecting all you external devices except video,mouse, keyboard

I agree with Dave but if you haven't done that yet turn your PC on and listen for any beep codes. It will sound like morse code. The lights arent' the only diagnostic device on that PC. But again Disconnecting everything one installing one at a time will probably get you your answer.

Thanks for replying, Davet150.

 

Same result. Also tryed without the keyboard and mouse; no change.

Thanks for trying to help, cd60.

 

The computer does not produce any sounds or tones at all.

The keyboard does not respond, so I can't bring up the F12 menu to tell the computer to boot off the CD. The process ends up stuck at the same spot as described above.

 

Does anyone have any idea what the "1_34" diagnostic lights pattern means? 

Open the computer. Disconnect the optical drives, If you have more than one hd and are not in a raid configuration disconnect all the hd except the boot drive,  pull out all but one stick of ram. Leave the stick in the slot closest to the processor heat sink. leave all external devices disconnected with the exception of vidoe,mouse,keyboard, pull out all cards except the video card.

If after all this still no go, disconnect your boot drive, Leave only the video card in the system.

 

Normally undocument light means a motherboard failure. However when my hd died a little bit ago it exhibited some of the same symptoms as you described with the slow bios post and funny diagnoscit lights.

Try putting in your Vista install disk and hit the repair tab and follow what it tells you to. There will be a choice for problems with restarting your PC. Give that a try.

One more thing to try because it happened to me last night. Having similar problems to you. My keyboard was working fine normally as well except during startup when it would say keyboard failure. So I tried a known good keyboard, which fixed the problem. Went down to Staples got a great deal on a wireless keyboard and mouse combo for $28 on sale. All is well now. Just another thought for you to try.

This problem can also occur if fast boot not engaged in BIOS check boot options in BIOS make sure fast boot engaged. Press f12 on startup Dell screeen appearing and release when u hear beeps, scroll down to boot options and ensure fast boot engaged.

The problem seems to be fixed.

 

When I cut power to the CPU to start on what Dave suggested I heard something inside the case 'click'. On a whim I turned the power back on and pushed the power button. The computer started going through the boot sequence at normal speed. I had Dell's hardware diagnostic CD in the drive so I booted off of it through the F12 menu. The tests did not report any problems.

 

When I let the computer boot up all the way, the OS for some reason reloaded all the external devices drivers. As far as I can see everything is back to normal, all diag lights on the front panel are off.

 

I don't know what happened. There was a heavy thunderstorm with a lot of lightning activity the night prior to this happening, so I  can only guess that this may have been a possible cause.

 

Thanks everyone for trying to help! Great forum and a great bunch of guys!