I'm really going out on a limb with this guess, but do you by any chance use AVG as your A/V? The reason I ask is because AVG will disable Windows Defender.
See AVG's FAQ #2672: "Windows Defender is automatically turned off during installation"
'Please note that Windows Defender is only disabled and not removed from the computer. This is important to prevent conflicts between AVG and Windows Defender. As they are both security applications, they will try to check files you are working with. Since they will do that at the same time, conflicts may arise. These can cause freezing, crashes or slowdown of computer. It is generally not recommend to use more than one security product on one computer.'
Let us know..
I have Windows Vista Home Premium "32 bit".
Been having some [popup problems)_. Think I've got that fix. ( I hope)
Now all of a sudden My Windows Defender is turned off. No matter what
I do it will not restart. I went to msn.com, and they had me going around in circles. This seems to be the best place to come to for help. So Help!
My computer is a (HP Pavilion a6230n PC)