I'm not sure if it is caused by my LCD monitor (samsung syncmaster 172n) or my graphics card (radeon x1900xt) Any idea on what might be causing this red line?
Try the monitor on a different PC or with a different graphics card to nail it down but if it's not the graphics card It sounds to me like you've got 1280 or 1024 dead pixels
hold off on the yikes, a line like that, if it was caused by a monitor problem, would not indicate damaged pixels, just innactive ones. It would likely be caused by some other part of the monitor actually being damages, and could possibly be repaired by the manufacturer.
You are about to answer a thread that has been inactive for more than 6 months. If you still wish to proceed, please ensure that your posting is original and does not duplicate or overlap any prior responses to this thread.