hi,
lines vertical or horizontal on the screen however intermittent may mean video card (or LCD but unlikely) is malfunctioning. run DXDIAG to test the display or use other video diagnostics like these (i have not tried these two before):
http://www.daionet.gr.jp/~masa/rthdribl/
or
http://freestone-group.com/download/...yTestSetup.exe