Hi all, I've recently installed Win 7 64 bit on T4215. Lately, I've been experiencing freezes with patches of yellow vertical lines on screen which I have to hard reboot. Also, I upgraded to 4gb of ram. I ran memtest86 just to make the ram isn't bad. It passed with 100%. I made sure all my drivers are current, but still I get random freezes with yellow lines. At that point, I removed win 7 64 bit and installed the 32 bit version and still got the same issue. I never had such issue when I was running XP tablet. Anyone else also experiencing this problem and might have a fix? Thank you.