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HP 520 constantly freezing

Last response: in Laptops & Notebooks
January 31, 2012 6:17:57 AM

HP 520
Intel dual core 2.2ghz
2gb ram
Vista SP2

Hi, my HP 520 notebook recently began to freeze up arbitrarily. everything stops suddenly with no warning. mousepad, keyboard, screen, harddrive etc. my laptop is set to shut down with a push of the power button- this does nothing. it's set up to just switch off the screen when the lid is closed but touching the lid-closed sensor button does nothing. it's completely unresponsive and the only thing left to do is to remove the power or push and hold the power button to force the power off.
this can happen at any time including before/during the HP splash screen, in the bios screen, while windows is loading ... any time. it seems to not be related to any stress or load on the computer, or any particular activity.

things to know:

i recently cloned and replaced the hdd. i don't envisage this being the problem. i've done it before with no probs and the machine was running for about a month with the new drive before this problem started.

i recently replaced the fan following these instructions:

this was a two stage process- the first time i only got as far as the keyboard before deciding i would leave it for another day....... two days after this the freezing started. research suggested the freezing may be caused by overheating so i completed the job, ensuring the build up of filth (there was a lot) was gone. also replacing the thermal material under the heatsink. the problem continued.

# the blue, wireless indicator light always goes out at the same time as the computer freezes (it can't be turned back on- the entire machine is frozen). i don't see how this could be related but am willing to consider it. manually turning it off when the machine is running has no effect on the freezing.
# lifting/moving the computer seemed at first to provoke the machine to freeze but it's certainly not a prerequisite.

things i've tried:

# swapping out/reseating the memory sticks. booting with just one, then the other one.
# memtest86 (no errors found).
# cpu temp testing- it rarely rises above 50 degrees. the computer has frozen with the display on the screen.
# opening up the case and checking everything was put together correctly.
# updated the bios.
# updated windows. (prior to this i was running vista with no service packs. i didn't expect the upgrades to help but tried just in case)
# disabling/re-enabling the wireless in the bios.
# chkdsk
# disabling/re-enabling dual core processor in bios.
# limiting to boot with one core in msconfig.
# Malware bytes anti virus. ran twice in safe mode.
# running machine in safe mode (has no effect- will still freeze at random).
# running machine with all combinations of power cord and battery.

i would love it if someone could provide a solution to this which doesn't involve buying a new machine! thanks for reading, i hope i've provided enough information.
February 1, 2012 5:02:20 AM

i am now convinced that this has something to do with the WLAN module, although i can't fathom why it would have such an effect. here's what happened:

i disconnected the antenna cables from the WLAN module and booted the machine. wireless light still comes on, machine still freezes.

i reconnected the wires and booted. this time no light, no wireless, NO FREEZING. how strange.

i checked in device manager and it didn't show a wireless adapter. i attempted unsuccessfully to find hardware. i shut down the machine and went into the bios. no wireless adapter was listed. repeat: it wasn't disabled in bios, it was showing no internal adapter, "built-in hardware' was greyed out.
i checked the module and found i'd connected the wires incorrectly. assuming this was why no internal device was listed i switched them around and checked the bios but still it showed no built-in hardware. i booted anyway and ran my machine for several hours, connecting to the net with a cable. no problems at all.
next i re-booted the machine and, lo-and-behold, the wireless light comes on! how strange. i run for a while, using both the cable and the wireless, also turning off and on the wireless button several times. no problems. i also check in device manager, which reports that the wireless is functioning correctly and drivers are up to date.
next i shut it down, just to have a look, "built-in hardware" is no longer greyed out. since then my machine has run without the freezing problem.

it seems to me that somehow the WLAN module has been uninstalled and then re-installed itself.

just to be clear, i've never removed this hardware, never disabled it through windows, never messed with it in any way other than the time mentioned in the OP.
does anyone have an explanation for why a malfunctioning WLAN module would have such an effect?

this is the wireless adapter: Intel(R) PRO/Wireless 3945ABG Network Connection

the final thing i did, although i have no idea whether or not it will have any effect, was to uncheck "allow computer to turn off this device to save power" box.

if anyone else is having this freezing problem- it's very common but i've yet to find a solution from web searches- i suggest you disable the wireless and take it from there.
February 2, 2012 7:46:21 AM

well, i was wrong. the wireless thing seems to have been a red-herring.

after running overnight and well into the next day i decided to pick up my lap top to place it on my lap, a few seconds later - freeze.

still thinking it may be something to do with the wireless card i physically removed the card from the machine but the machine would still freeze randomly as before.

so now i'm back to square one. anyone have a possible cause for this common and quite serious problem?