In order to install Windows on your system, you must activate the product using a valid product key. After you enter a product key while installing Windows if system reports it invalid, the possibility is that you have entered a wrong product key. But if you are sure that the key entered is valid, there might be several reasons causing this behavior including hard drive damage. In case of hard drive damage, you need to replace it and restore lost data from backup. But if backup fails to restore, hard drive recovery solutions come as rescue.
 
While trying to install Windows XP on your computer, when you try to enter the product key, you encounter the similar error displaying on screen:
 
"The CD Key which you entered is invalid. Please try again."
 
You might also receive an error telling that the product key used is invalid.

Cause
 
The above error might be the outcome of below possible reasons:
 
1. Using an invalid product key
 
2. An antivirus program is scanning the computer
 
3. Windows XP installation CD is damaged
 
4. Hard disk is damaged
 
5. Incorrect system date in CMOS  (Complementary Metal-Oxide Semiconductor) settings
 
6. Some extra drivers are installed that are interrupting the installation
 
Solution
 
You should follow these steps to solve the existing problem:
 
1. Make sure that the product key you are entering is correct. Try making use of keyboard number keys instead of numeric keypad
 
2. Disable antivirus software scan. You need to ensure that no antivirus software is turn in computer BIOS
 
3. Replace the Windows XP installation CD if damaged
 
4. Ensure that the hard disk is not damaged. If it is, replace the hard disk and restore lost data from backup. Contact hard drive recovery service professionals if no or invalid backup is available.
 
5. Verify CMOS settings for correct system date
 
6. To provide clean installation of Windows, restart Windows without the installed extra drivers
 
7. You can also try copying Windows XP installation files to hard drive using command prompt
 
Hard Drive Recovery
 
It is the dedicated help provided by recovery experts to recover lost data from physically crashed drives. hard drive recovery software professionals undergo several sophisticated processes using advanced techniques in Clean Rooms in order to recover the lost data.
 
Stellar Information Systems Limited is the leading organization with highest success rate in providing safe hard drive recovery service. Its service caters all types of hard drives, including SCSI, SATA, IDE, EIDE and PATA. Stellar has Class 100 Clean Rooms and industry's best recovery experts to facilitate advanced data recovery.