I have called Bit Defender tech support about this issue, after placing me on hold, they "escalated" my issue. In an email I got from tier-2 support, the file they referenced in the email simply wasn't there so I couldn't take the steps they wanted, when I called back they basically said "sorry" and that they're try harder next time. Seeing no resolution at all from the phone support, I decided to post my issue here before I take further action.
I have Bit Defender Internet Security 2013. I scanned my computer a few days ago; after the scan, it said there were "critical issues to fix". When I clicked on the issue, it stated "On access scanning disabled" and when I click on "start" to fix the issue, it says it failed. When I click close, the dashboard is greyed out, and it says "Your Bitdefender license is invalid" and I have three buttons to click, "Buy Now; Register Now; Contact Support". When I click on "register now" it brings me to a product registration screen that prompts for a license key, and there is a license key displayed on the left-hand side of the screen. When I put that in, I receive the following error: The license key you have entered is currently used in the product. You cannot register the product twice with the same key.
When I called support and gave them the license key, they said I had a lifetime key (which I bought) and had no clue why this would happen. I'm about at my wits end with phone support, having wasted so much time with them, so I'm hopeful this issue can be resolved out there by someone. I've tried right-clicking the bit defender icon and updating the product, but this issue still persists.