AVG suddenly does not recognize valid product key. There are no active components

All these while, my AVG product working well. Suddenly it is having problem in invalid product key. The AVG required me to insert the valid key again. I'm try to insert the key, AVG detected it is the valid key and reactivated it. It seems nothing change after reactivate it.
I tried to uninstall the product however the uninstallation failed due to error code below.
Error code: 0xC0070643
Description: Event exec_finished
I tried also to repair it but i'm getting the same error which repairing failed. 
Can someone please help me how to troubleshoot this issue.

Hello Eric,
Thank you for the brief explanation of the issue.
We apologize for the inconvenience caused. Upon carefully reviewing your account, I see that there is no active product found in your account. Due to security reason it is advised not to post personal information in public thread. We request you to contact our live chat support to get the issue fixed. Click on the following link https://support.avg.com/support_contact_form?l=en_US&retUrl=support_Internet_Security and fill out the form and choose "Chat" option one of our representative will help you with it.
Feel free to contact us for any further assistance. Thank you.

Hello Eric,
We regret for the inconvenience caused. Please check whether you have installed any other conflicting applications like McAfee, Avast, Norton etc… on your PC, If so please uninstall the conflicting applications.
If not, please  click this link http://aa-download.avg.com/filedir/util/AVG_Remover.exe to download and run the AVG Remover tool to remove all the traces of the AVG.
1. Please select the AVG products which are shown in the remover tool window and then start removal process.
2. After the remover tool process is successfully finished, restart your computer.
3. After the restart,  manually delete the AVG Remover folder in the C drive of My computer.

Eric, General info… What Windows OS are you using?.. Before Win 8 Windows Defender was only an anti-spyware product. Since Win 8 was introduced it's been re-classified as an anti-virus product (https://en.wikipedia.org/wiki/Windows_Defender) so it's possible that it can conflict with AVG so that's why it's turned off/disabled.
AVG Guru

Hello Eric,
I would like to keep you informed that 'Windows defender' will automatically be turned off/disabled once you install AVG. Hence it is not required to manually uninstall 'Windows defender'. However after installing AVG, you should not be finding difficulties like system slowdown etc. If you experience such difficulties(while or after installing AVG), please let us know. Thank you.