I've always left my pc on during the night time for back up and updates. The memory usage usually varied between 50-65% while idle during the day. I've been doing this for a couple of years. Recently my memory reaches upwards to 80-90%. I have PC Tools, and it cleans and optimizes weekly. And I've deselected programs in the background not to run if they don't have to. The high memory usage slows the computer down.
I've been rebooting often now, and that temporarily fixes the problem. But it will start about 50% usage to 90% in about 3 or 4 days. Anyone have any ideas here? I'm running Windows 7. Installed memory is 3GB.