As soon as the Vista screen loaded, though, the monitor was covered in green, horizontal, flickering lines (from top to bottom). The desktop loaded, but the screen was barely visible due to the lines.
After a few restarts, the desktop will not even show up anymore. The vista screen goes straight to black (with green flickering lines).
When I boot in safe mode, everything appears completely normal. No lines whatsoever, which makes me think it's not a monitor issue.