black screen sometimes

hello,
I am having a problem with my HP nc8230 laptop.
sometimes on powering up, i get a black screen before even getting the bios info to to press F10.
and sometimes, i turn on normally and i log on to windows XP as nothing is happening.
after opening it, i checked and the connectors are placed correctly, i tried to clear the ROM, i tried to disconnect to CMOS battery, i tried to troubleshoot the CPU. i tried to see if it's the RAM...however, still getting the same problem sometimes i log on normally and sometimes i get a black screen and the CPU fan doesn't stop.
can anyone help me plz with this, probably it's a hardware problem... because i am not geting any error while being able to log on to windows, any blue screen any interupt...very weired.
thx in advanced

 

That is generally a sign of the computer (BIOS) not being able to communicate correctly with a piece of hardware. Since laptops are all "standard" as far as the internal hardware is concerned, you could only check those things that are plugged in. So check everything that can be inserted/connected. Read through the User Guide it should tell you how to locate some of the parts (like changing the RAM or the main battery). Pull out and reseat those items. There will also be a CMOS battery which looks like a silver coin, replace that if it is removable.
Also check that say, the USB connectors or the PCMCIA connectors do not look damaged.

Some of the people that have had problems with their laptops have opened them up themselves and found and repaired the problem. Again, see how helpful the User Guide is or there may even be a service manual for download at the HP website. Hp have a user forum, it may be worth searching or asking there.

Matt
Edit, sorry, you did check a lot of those things. I read it yesterday and did not reread before posting. Hope there is something useful. If you can disconnect the connectors, pull them out and reseat them, they may look OK, but the connection may still be bad.

 

Two more things.
What LEDS are lit when it "blackscreens "? That may mean a drive problem if the same drive LED is lit every time. If it is the HDD LED, run the drive diagnostics that you will find at HP.
You can try running the memory diagnostics in my signature.

Matt