I used to have the same problem.
After the old, rebuilt, upgraded, taped together computer finally breathed it's last and I told the wife, "I ain't goin' through this anymore!", we went and bought a brand, spanking new computer, got it all set up and I haven't had that problem since.
I don't think it is the new computer, exactly. But, it sure is nice not having all the problems I used to have.
Randie