I've been using Windows 7 for the past 10 days. For the past few days, whenever I turn on or reboot my computer, after logging in, I am shown the main Windows Defender window, which says it's running normally. It was not like this the first several days after I installed Windows 7. I don't know what I could have done that makes the Windows Defender window always appear at start. If I try to disable Windows Defender or switch it to manual, then on start up I get a small window with the message that Windows Defender is not running, and I can click OK or there's a link to enable it. Like I said, I just this Windows Defender window to not be displayed on start up. I just want it to run in the background. Any help fixing this would be greatly appreciated. Thanks.

you can try to disable the windows defender start up entrie: here is how...

Thanks for posting that link, probfixer. Like I said in my post, I don't want to disable Windows Defender, just stop the window from appearing at start up, even when there's nothing wrong. But I'm so annoyed by this, I'm willing to try anything. So, as suggested on that page, I used msconfig to uncheck Windows Defender on the startup tab. I rebooted and logged in and no Windows Defender window! I then checked Windows Defender's status using services.msc, and it said Windows Defender was running, which was great. One weird thing I noticed when I used msconfig is that at the end of the command for Windows Defender it says "-hide". None of the other startup entries had this. I don't know if this means to hide the window or to not hide the window when it starts. Since the command isn't editable from msconfig, I used regedit to remove -hide from the end of the command. I reenabled normal startup in msconfig and rebooted, and again, no Windows Defender window after logging in, and yet it's still running, just like I wanted. Thanks!

you`re welcome pal... :-)