Hello & Welcome to SevenForums!
Is your Windows 7 making a Restore Point, Updating etc?
Try also to disable your anti-virus, just to see if something is happening.
An idea, could be to type msconfig.exe, go to the startup-tab and see what is starting up when Windows 7 is starting. Un-usefull applications, software etc should be ticked as off.
You could do this in CCleaner also. Startup Programs - Change