Hi experts, I had a perfect running system for more than 6 months. AMD 2.4 Ghz Asus M2NMX-SE plus mainboard. 4 GB DDR2 Ram ( 2 X 2 GB). wINDOWS 7 Ultimate 64 bit. Problems started when I got a new video card ATI radeon hd 5450 1 gb. When I installed the card and the drivers, there was...