HP Compaq 6515b laptop: Diplay is blank, Few times it came back after some time, But now it is titally blank,

Sir. Replace your AGP card

I had to fix this problem a couple years ago, it's common on Compaq's. The only way to fix it is to short out the CMOS battery on the motherboard. Doing this voids your warranty, so if you wish to follow that course I cannot tell you exactly where to go, but google's your friend. The other option you have is to call Compaq and open a ticket with tech support. If your laptop is still under warranty, you may even get a new computer.

1st method identfy bios when start up " AWARD BIOS, AMI BIOS,etc etc below some backdoor passwords try these first
Award BIOS' :

AWARD_SW, j262, HLT ,SER,SKY_FOX,BIOSTAR,ALFAROME,Lkwpeter,j256,
AWARD?SW,LKWPETER,syxz,ALLy,589589,589721,awkward,CONCAT,d8on,CONDO,j64,
szyx.
For AMI BIOS' try these backdoor passwords:

AMI,BIOS,PASSWORD,HEWITT RAND,AMI?SW,AMI_SW,LKWPETER,A.M.I.,CONDO.
For PHOENIX BIOS' try this backdoor password:

phoenix

2nd method: remove the laptop battery, and in back of your laptop 3 to 4 screws showing small keybord pictured or keyboard mark, remove those screw's, turn front and 3 little hidden clips upside of keyboard, slide down those clips, carefully remove the keyboard, in motherborad near touchpad, locate the small silver color coin battery, remove that battery for 1 minite or 2. and put it back. your password will reset. and also bios resets to factory setting.( before resetting just write down the setting on paper) best of luck keep smiling. aaarwind

I would sort your BIOS problem out first. Fit a new CMOS battery and set date, time etc. Then it should recognise the hard drive.

Your harddrive is starting to go. You will need to replace your hard drive. When you computer starts running slow then it reboots itself is because it is trying to get itself to work properly, but the hard drive is not operating at full capacity. I would back up all of your files as soon as you can onto either a CD or a flash drive, to save yourself from very costly repairs if you need to have the data extracted from the hard drive

Laptop motherboards have built-in video graphics chips and therefore you cannot upgrade the video card. There are no expansion sockets available for graphics card upgrades.

replace the seaker of laptop

If you are using Windows XP Go to this page and look under the security section.
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareIndex.jsp?lang=en&cc=us&prodNameId=3355651&prodTypeId=321957&prodSeriesId=3368537&swLang=8&taskId=135&swEnvOID=1093#7887
and download the appropriate driver

press.alt+ctrl+f1

The issue you are having is on the Cisco side. The router will have to be opened or set to allow the connection of these devices and depending on how you have the router setup you will have to configure the Hp's with either static or dynamic ip addressing, of course the static addressing is the least secure. But either way pull up the wireless options on your 4400 .you should have a key to logon machines because i am sure there is some encryption on your server/routers.

http://www.cisco.com/en/US/products/ps6366/prod_configuration_examples_list.html

this is the link for this product and setup/configuration:

its very detailed, but depending on your IT or admin there you need to know how to configure or search existing information on the unit.

once you got it set or know the key then plug it into the laptop to provide access to your wireless network

Good Luck!
Ruben