If you are using Windows 8 and if you want to use it, you need to delete your dsdt.aml from Windows 8, use the dsdt.aml provided by Dell if you have it, and activate the copy of Windows 8 on your computer.
I'm not sure of your situation, but if your firmware key is 6A6F004B0000, then that is a valid product key for Windows 8 and your Dell OEM copy of Windows 8 is not activated. Your system is still under warranty. There is no need to reinstall as the activation status of Windows is already correct.
I also noticed that you are using the dsdt.aml file provided by Microsoft that is for windows 8. It will not work in windows 7. If you're using dsdt.aml from a windows 8 install, you are using the wrong dsdt file. Use the dsdt.aml provided by Dell if you want to use it on your computer.
If your dsdt.aml is from Windows 8, I have no idea what to tell you, but all I can do is speculate. The dsdt file was modified to only specify the OEM key not the SLP key which is needed for activation. I don't know if Dell ever used the dsdt.aml from Windows 8, but if they did, it is not valid for use on Windows 7.
If you are using Windows 7, please look at my post above and use the dsdt.aml provided by Dell if you have it. The product key is not 6A6F004B0000. If you want to use a new Windows 7 copy, that is ok, but you need to use the dsdt.aml provided by Dell if you have it (I linked you to the right page). There is no need to activate your OEM copy of Windows 7. 827ec27edc