As an addition to what Jholland mentioned, is there a pattern to when these lines are appearing or correlation between running any programs and the lines appearing? If so it might be a conflict with the running program in question or at least an isolated issue in a similar fashion.

If you have not updated your drivers or made any changes to this system then I wonder why the lines appear now if it was indeed the driver? Main suspects would be a service pack or system update or another device driver you might have recently installed or updated.

To find the culprit on a system that appeared seemingly out-of-the-blue, I always follow Columbo's crime scene logic:

- What is there that wasn't there before? Newly installed programs, device, system update or service pack, etc.
- What isn't there that was there before? Uninstalled program, device drivers, deleted folder, file, registry key, etc.
- What has/was changed? Modified or moved registry, file or folder meaning system or application setting, BIOS configuration, system service, etc.

I guarantee you will find the culprit if you can answer each one of those questions.