For about 2 months now, my computer occasionally freezes with vertical lines on the AMW LCD Monitor Model Number MR17-D1AD. This morning I did a system restore to an earlier point but this did not fix the problem. Several reboots later and the PC has been running fine now with no problems for about 14 hours. This is an intermittent fault and I am trying to establish whether it is a hardware or software problem. Sometimes the computer runs fine for days and then I will get the vertical lines on screen and a freeze, requiring a reboot. Does anyone have any indication as to what might be causing this?