:confused: purchased the compaq N400c laptop a couple of days ago (second hand) and has been working fine until today. I cannot access windows at all. Does anyone out there know about this model. Have checked the guide book for troubleshooting but lists nothing like the problem that I am having. Any comments appreciated.

Not sure, at the following site you can either have a chat with a tech or email them for support: http://h18000.www1.hp.com/

Hope this helps!
Whiskey14

What are your symptoms? Does the laptop start up? At what point does it fail?

Have emailed tech support they not interested as computer is out of warranty.
Wot is happening is after you switch it on you get a black page with white writing saying theat there has been an error and start in safe mode,last mode when it worked properly etc.there are a few options then it goes to the windows screen as if to load welcome page but doesn't, it goes straight back to the black screen with the countdown to loading,no commands work at all.The only thing I can think has triggered this is the installation of a card to enable me to connect to the internet wirelessly.I do not have back up discs only purchased it a couple of days ago.

What exactly is the error? Can you start in Safe Mode? What version of Windows are you using? Have you tried taking out the NIC, card for networking?

Taken card out and no it will not let me start in safe mode, I am running windows professional

The error reads "your computer is unable to start this may be due to recent installation of new hardware"

As this is a new computer to you, you probably don't have anything on there to lose yet do you?
What media did you get with it, any recovery cds or windows cd? If you have these and are not concerned about any information on the machine, I would re-install the operating system.
To do this you just need to make the computer boot from CD-rom (in the bios) and insert the windows or recovery cd and boot from it. However, as this is a laptop, you might have some issues with drivers if you don't have a recovery cd. Therefore I would look at the hp site and download any drivers you can find for your laptop before you begin.

The system is windows professional and I do not have any recovery cd's but I do have recovery discs for windows XP would this work?
If not I will try downloading

Assuming that the disc you have is the same version of XP, then you should be able to attempt a repair of the OS.

Here's how to do a repair of your XP install.
Here's some instructions that should help:
*Put your XP CD in the drive.
*Turn on the computer
*Look for message "booting from CD" usually located at the bottom of the screen. If you have a factory splash screen, press ESC to unload it.
*Press any Key when you see the prompt to 'Press Any Key"
*Setup will start copying files, if you need to install any third-party or RAID drivers press F6 at this time. The copying of files can take awhile.(leave this one)
*Next you will get the option to repair or enter setup, choose to enter setup. Press ENTER.
*Press F8 if you agree to the license.
*Setup will scan for previous Windows installations
*At this point it should give you the option to repair the highlighted installation of install a fresh copy
*choose repair highlighted installation.

Leave to cook for 30-40 minutes
Hopefully this should fix your problem and you should be able to boot into windows normally.

This DOESN'T wipe your current install only overwrite changed files.

Many thanks for all of your help I will try that and let u know what happens.