Wednesday, October 24, 2007

Notebook computer woes

This is a very sad and nerdy posting, but those who have spent hours or days tracking down computer faults will know the state of mind that it creates, and the consequent need to drink large amounts of beer and write drivel!

I bought myself a new notebook computer (HP Pavilion dv9340ea) three months ago, and would you believe that a fault has already developed? Luckily, the fault turns out to be fairly benign so I can continue to use the computer, but the fault continues my unbroken record of always managing to buy notebook computers that go wrong.

What is the fault? The graphics display developed a habit of locking up with no warning, and the computer would then reboot showing various regular patterns on the boot screen, and then go to a "blue screen of death" (BSOD) informing me that nvlddmkm.sys had thrown error 116. The computer would then reboot again offering me the choice of booting into a "safe mode" of Windows Vista, which I duly selected, and I was then allowed back into the machine. At least I could get at any files that I wanted to extract from the computer.

So, off I went onto the internet searching for information about nvlddmkm.sys and error 116. In turns out that you can find lots of complaints about nvlddmkm.sys, which I found perversely gratifying because it meant that I had company. Various wise individuals offered solutions to this problem, which mainly focussed on manually uninstalling the old and buggy graphics driver (i.e. nvlddmkm.sys) and installing the latest version of this driver. I did this but it didn't fix the problem. I repeated this process several times, steadily enlarging the scope of my manual deletion of old files before installing new files, but I completely failed to fix the problem.

Maybe my nvlddmkm.sys problem was not in fact the same as the one that could be fixed by updating the graphics driver. Apparently, error 116 is quite a general fault that could be thrown by almost any error condition in nvlddmkm.sys.

I then did a full virus scan but it found nothing unusual.

I then decided to pay more attention to how my computer behaved without any special graphics driver installed. It showed the same regular patterns on the boot screen that preceded the BSOD that I mentioned at the start of this posting, but the BSOD itself did not occur, and I could boot into normal (i.e. not "safe mode") Windows Vista, so I had all Windows services available to me, but the screen resolution was relatively low because there was no special graphics driver installed.

The only other sign that something was wrong was a strange coloured granularity that showed up in what should have been featureless regions of colour on the screen. On rebooting, this fault occasionally disappeared, so I tried various experiments to check whether it was a thermal problem that went away temporarily if I switched off for a while. No luck there. I could not find a systematic way of influencing the fault.

In desperation I tried tapping the computer case with my finger, moving around all over the case, both on top and underneath. I noticed that when I tapped in one particular place under the case the strange coloured granularity disappeared at exactly the moment that I tapped the case. Jackpot! Although the fault quickly returned, and after a few repetitions of this cycle I eventually couldn't get the fault to go away at all, I had now absolutely convinced myself that my computer had a hardware fault that was probably in the graphics subsystem.

A loose memory chip maybe? The only memory that you could fiddle with was system RAM not video RAM, so reseating the system RAM modules didn't fix the problem, nor did I really expect it to.

However, I managed to find some photos of the system board of my notebook computer, and I noticed that immediately under the area of the case where I did my few successful taps was ... drum roll ... the graphics subsystem. I think this fairly convincingly demonstrates that something has gone wrong with the graphics hardware in my computer.

Now, all I have to do is to convince whoever it is that actually fixes my computer that they don't need to reformat my hard disk to check whether doing so cures the fault. In fact, it would be really nice if they would simply bring out a new system board to swap with my faulty one. What's the betting that things will not go as smoothly as this?

Update: After multiple emails and phone calls to HP they have agreed to service my computer under warranty, but they insist on restoring my hard disk to its factory settings. Resistance is useless! Since I don't relish going through the whole process of reinstalling all of my software, especially since there are lots of fiddly little things you have to do to get some of my old Windows XP software to work correctly under Windows Vista, I have decided to buy some disk mirroring software (i.e. Paragon Drive Copy 8.5). This software spent 2 1/2 hours mirroring my notebook computer's hard disk, and then announced that it had successfully done the job. Do I believe this? Do I believe that if it has done this part successfully, then it will also do the reverse mirroring successfully when I get my computer back from HP? I don't know what to think, but at least I have tried, and the Paragon software didn't cost too much (i.e. £30).

Update: Finally, after further phone calls to HP, they have agreed on specific dates to collect & return my notebook PC for its servicing-under-warranty. My main criticism of this process is not so much the large number of phone calls that I had to make, but the fact that HP uses call centres staffed by people who speak fluent English but with an impossible-to-understand accent. I had to ask several times for things to be repeated, and only with a certain amount of ingenuity and prior knowledge on my part could I understand what was being said. On more than one occasion I had to abort the phone call because I couldn't understand the accent at all, and on one occasion they aborted the phone call because of my inability to understand them!

Update: Finally! My notebook computer is back from the HP repair centre. The repair notes state that it had exactly the problem that I had originally diagnosed (i.e. a video hardware fault), and that the repair was a straight replacement of the motherboard. I hope that this fault was merely an "infant mortality", and that now I am likely to have years of trouble-free operation.


Anonymous said...

i have the same problem with my hp dv9220us for few days. Do you repair it ??

Anonymous said...

have you tried to flash bios to your hp. It seems that it help. Form about 1h my computer works :)

Stephen Luttrell said...

I have now managed to convince Hewlett packard that my computer has a "hadware issue", as they like to call it. The problem is in the graphics subsystem, and it is definitely a hardware rather than software fault. HP have invited me to call a special telephone number to arrange for it to be serviced.

I had previously downloaded the latest version of the BIOS from HP, but I didn't install it when I realised that the problem was a hardware fault.

Was your fault exactly the same as mine? here are snapshots of my boot screen that show some symptoms of the problem that I have:
"Snapshot 1"
"Snapshot 2"
The fault shown in these snapshots appears only after the computer has warmed up, and these snapshots helped to convince HP that I had a hardware fault.

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