Game randomly freezes, requiring full restart of computer

For the last week or so, my laptop will freeze, and half of the screen will be covered in fine vertical green bars. When this happens, the computer becomes unresponsive, and needs to be restarted. This occurs only when I'm playing FFXIV on the laptop. Sometimes it happens after 30 seconds, sometimes after 15 minutes. Last night I played for 2 hours with no issues. This issue has not occurred outside of FFXIV - using the computer for email, television, or even other video games is fine. The laptop does not appear to be getting any hotter than usual.

The laptop is about 5 years old, running windows 7. It is an MSI CX70. It has never had any issues like this before, and has been used for prolonged video game sessions for years. The only change I can think of is that I moved a slightly more moist environment a few weeks ago. If anyone has any advice on how to fix this, it would be appreciated.

Picture of what is occurring https://ibb.co/f9JkKk