Every time I start my computer, the "This copy of Windows did not pass genuine validation" appears on my scren and unable to disappear

You copy of windows in not genuine or registered as it has gone for auto updates to Microsoft wherein the error has been detected.
SO have the OS reinstalled maybe with the valid certificate.

It means that the copy of microsoft windows installed on your system in not a Genuine Copy (not original, duplicate copy). If you purchased it from a retailer or from an online store etc.. you can complain them about this issue. We can get rid of this notification, but it's not legal. So I don't recommend the method, but instead you proceed with the complain. I hope you understand what I mean.

If you need further help, let me know.

Good luck.

Thanks for using FixYa.

indows Genuine Advantage Notifications for Windows XP notifies you if a copy of Windows XP is not genuine. The notification messages only appear on computers that have failed the WGA validation process and that are running a copy of Windows XP that is not genuine. If you are running a validated, genuine copy of Windows XP, you will not receive notification messages.
http://support.microsoft.com/kb/905474

Whenever you get a genuine windows validation error you must contact Microsoft to find out why you get the message.

Temporarily you can get rid of the message doing a System Restore to a date before the genuine windows validation error appeared for the first time.

To do system restore you can go to
Start button>Programs>Accessories>System tools>System Restore.

The main issue is that your windows got expire and its time to activate it once again. It needs to be activated always in order to stay genuine.

To do that either you have to purchase the windows key or activate it via a tool.

Read here the full process -

Activate windows via key

message appearing on the screen that you may be a victim of software counterfeiting.this copy of windows did not pass geneuine windows validation. hiiii this is msg displayed on my screen
software counterfeiting,did not pass genuine windows validation problem,

you have to format your computer than you install other software

It might be a pirated windows version.Contact the vendor and check for the serial number of the disc provided to you.Please do rate If this could solve your problem.

This sort of issue takes place usually after windows updates
Therefore the best solution is to uninstall the recent updates on your computer and restart again.

install genuine windows or entre genuine windows key