windows needs activating after approx 6 months

i have been using windows 8 pro x64 with media center since around the time it was released and i took advantage of the upgrade offer, and up until about a week ago everything was running smoothly as expected. now in the past few days it says it needs activating and when i try to activate i get an error message, the control+alt+delete results in a delay of about 15-20 mins followed by an error message saying task manager wont open. i have not changed or added any hardware or my system configuration at all, apart from software.

i ran SFC scannow and it found and fixed some corrupt files but the symptoms still remain the same as described after a restart.
can anybody suggest possible fixes, or do i need to reinstall........................

Gazzer

Open the elevated command prompt, type rstrui.exe then press <Enter>. Look in the list to see if you have any restore point created from the previous week when your system was stable and restore it.

how do you get a command prompt in win8 ?. i also forgot to mention that when i try to open the activation wizard or open system restore there is a delay of 15-20 mins at least usually followed by an error message.

Hold Win Key + X, you'll get a popup menu from the bottom left corner and select Command Prompt (Admin)

done a system restore as suggested but no change. here are some error codes i am getting

error code 0xc004f015
the software licensing service is not installed

Most problems relating to that error seems VL based - if your system was KMS activated before updating to WMC then that is not a legit upgrade path and will get flagged.

do i need to reinstall........................

Click to expand...

My answer to that would be an unequivocal Yes!