May need cleaned out. Just because you don't feel heat does not mean it's not heat related. Could be heating up so fast (Processor) you don't get a chance to feel it.

Google Clean vents on hp DV9910

Google Over heating hp DV9910

Thanks zep516! This PC has been cleaned regularly. But I did google the topics you suggested and am in the process of following the instructions. So far, no change. Any other suggestions will also be welcomed.

Modern processors are designed to slow down or shut down when they overheat to protect them from damage. What concerns me is the purple lines on the screen. I'm thinking something related to the graphics chipset, screen itself, or the cable that connects the two. Unfortunately laptops are difficult to troubleshoot because replacement parts aren't readily available. With a desktop you could, for example, switch out a video card to troubleshoot this kind of problem.

Generally speaking with the exception of memory and hard drives, laptop repairs aren't cost effective for low to moderately priced machines.

Well it sounds like a catastrophic failure when it shuts down like that. You can't fix them by running scans or things like that. You can't access the system to do anything!

The only other advice I could offer on a problem like this is to restart the laptop and keep hitting the F8 key. Wait for the advanced options menu to show, white letters on black screen. Using the arrow keys select "Last Known Good Configuration. Form your description though I do not think you will get that far.

Take the battery out try just the AC adapter etc.

Over the ownership of a laptop there usually in twice for major repair.

The only time I'd purchase one is if I absolutely had to have one for portability reasons.

Thanks for all the input. I did try hooking a monitor to the laptop to eliminate the possibility that it was just the screen or the cable that connects--it showed nothing.
I agree that the repair may not be cost effective--but wanted to try everything I could before purchasing another PC.

Also just tried Zep16's advise to keep hitting the F8 key, but just as he suspected--the menu never appeared.

Although laptops are difficult to troubleshoot because replacement parts aren't readily available. We do have 2 of these laptops exactly alike and I wondered if it would be advisable to switch out the hard drives, etc... to see if I could pin point the problem. Since my knowledge is limited, I wasn't sure if taking the hard drive from the working machine was a good idea.

Thanks again--All input appreciated.

I don't think it's a good idea. If you decide to do it Google disassemble HP Pavilion DV9910

You might find half way good instructions. My guess it's a power / Motherboard issue. A hard drive failure would usually provide an error. Blue screen error. But not always.

Thanks... I have changed hard drives, memory, etc, but the motherboard is something , I don't think I'd feel comfortable working with..so I do really appreciate your advise. I will Google the HP Pavilion DV9910 and just see what I can find, but it is looking like I need a replacement. Thanks again everyone and other suggestions are always welcome.

I had a problem just the other day where the APM (Advanced Power Management) got messed up. Some of my symptoms sound like some of the symptoms you had when you tried to start up.

Here's what got me going again:
1. Unplug everything from the laptop.
2. Pull out the battery.
3. hold the power button in for 60 seconds (time it because it seems a lot longer than it is when you're sitting there holding the switch in)
4. Put the battery back in.
5 Plug in the power.
6. With nothing else attached (no printer, mouse, microphone, earphones, etc), try turning it on.

If it works, you can try plugging in peripherals one at a time. If it doesn't, then you're having a different problem than I had.

Thanks, bpgreen..I tried it and it didn't work, but I was so hoping.
When the power is turned on the Laptop, it makes a noise like it is going to boot up but all the lights cycle on and off until the battery is removed. It will not turn off by the power button. However, if you hit Ctrl-Alt-Del the lights stay lit and it doesn't boot up, but it will shut down with the power key.
Again Thanks! Any input appreciated!

i dunno... HP site;

Here is a link that might be useful: DO THIS FIRST - Perform a hard reset

Don na na wrote I have changed hard drives, memory

What exactly did you do? In my opinion having removed these things you should have tried the good hard drive in the defective computer and the possibly bad hard drive in the good computer. Same with the memory but not at the same time. That way it helps eliminate things perhaps. You might even try swapping the power supply seeing you have twins. At least this would eliminate those 3 items - or find the cause with one hopefully.

I think what she meant was that was the extent of her knowledge and what she has attempted to do in the past not what she has done to this particular pc. That is how I took it anyway.

There are disassembly instructions for some HP laptops and the newest on this list is a DV8800...if you have to start a disassembly, this may be helpful to get you pointed in the right direction

Here is a link that might be useful: HP Maintenance manuals