OK, I have been doing nothing different than I have been since I have gotten Windows 7.
Now all of the sudden Windows Defender is turned OFF and I cant turn it back on.
It tells me that it is blocked by group policy.
It is likely that you have become infected by malware of some sort - it is very common for such software to try disbale tools that could remove it. Try booting Windows in Safe Mode and running scans with other known-good tools like adaware (by "known good" I mean don't use anything that you don't know the quality of or that you have had recommended by a trusted source - most anti-malware tools advertised on the web are actually malware themselves), or defender if it will start in Safe Mode.
If you are running Microsoft Security Essentials, you do not need to run Windows Defender. Microsoft Security Essentials is designed to disable Windows Defender in order to manage the PC’s real-time protection, including anti-virus, rootkits, Trojans and spyware.
Microsoft Security Essentials should disable Windows Defender on Vista and Windows 7 and uninstall it from XP. In some cases, this does not happen automatically.
If Microsoft Security Essentials did not automatically disable Windows Defender on Vista or Windows 7, you should disable it to prevent conflicts. Windows Defender cannot be uninstalled from Vista or Windows 7.
If Microsoft Security Essentials and Windows Defender are both running, your system may experience performance degradation and other problems caused by the conflict of two services providing real time protection simultaneously.
Source: Microsoft Social Answers.
defender is outdated and has been replaced by microsoft secruity essentials look to see if that process is running.
Have you installed antivirus or internet security software? The newer ones seem to suppress and override Defender, since they are more complete solutions.
I do run Windows defender in safe mode with networking so I can update defender and run a full scan, but I only do it once a month.
That does make sense that Security essentials blocks defender but it seems defender will catch all the adware or malware your PC may have?