I need your help because I'm in big trouble again. I was asked by one friend of mine to reinstalled Windows and to clean up heatsink fan as his laptop is going off in 2-3 mins because of overheating. First I've reinstalled current Windows Vista to Win 7 Pro and laptop was working perfectly with newly Win 7 Pro installed. After that I dessambled the laptop, cleaned up heatsink fan, put thermal compound between cpu, nVidia chip and heatsink, plugged all disconnected cables back into the motherboard (I checked out everything twice), then turned the laptop on and as outcome nothing is coming up on the screen (black screen and no windows logo). the power light was on, hdd light was on, wireless light was on, all the lights were on but the screen was still black. Then I fixed this as I took RAM's out and put them back in properly. Then the laptop started booting up and I got message asking me ''where Windows to boot from'' ,and I pressed Enter button, got Windows 7 logo and managed to logon into Win 7, run Hot CPU Tester software to test the hardware, and as outcome the laptop passed through the 6 hours test successfully. Then after logon Win 7 started behaving strangely as when I click on Conrol Panel or Computer icon drop down arrow (next to Control Panel>All Control Panel Items or Computer) starts flickering and I cannot select any drive (C,D or CD/DVD drives). I thought it is something wrong with Windows and decided to perform clean installation again. Restarted the laptop and throughout the restarting process laptop started getting long beep signal and then I managed to boot from Win 7 installation disc. Then I got screen with what date,format and language to choose from to carry on with the installation and drop down arrows for the language and country started flickering again and I couldn't select correct language and country but then with help of Up Arrow button I managed to select the correct language and country and carried on with installation. Then I managed to delete partitions, created new ones, done formatting and carry on with the installation, then windows managed to copy and extract installation files as there were all green ticks and had to restart again. Then throughout the rebooting I got the same long beep signal and I'm back from the beginning of the installation, and cannot carry on further with it. Then I used WinXP disk, started Recovery console and run ''chkdsk /r'' command to fix and repair some hdd's bad sectors and errors. Then Run Win 7 installation again and got stuck again in the middle of Win 7 installation and couldn't finish it. Sorry for that as it's a bit complicated or I'm not clean enough with my explanation regarding to that installation issue.
What am I missing?
Where else to look into?
Is it motherboard issue or hdd issue?
Is it hardware or software issue?
This happened to me so the fault is mine and I have to sort it out.
Laptop model is HP Compaq Presario CQ50 with Win 7 Pro.
Please any advice will be appreciated!
Thank you in advanced!