There may be several possible reasons for restarting the computer when starting Roblox. Here are some of them:
Lack of RAM: If many processes are running at the same time and a lot of RAM is being used, the game may encounter problems when starting up or work incorrectly. In this case, it is recommended to close other programs and applications to free up RAM.
Graphics Driver Issues: An outdated, corrupted, or incompatible graphics driver can cause performance issues in games, including Roblox. Update your graphics driver to the latest version and check if the problem is fixed.
Software Conflict: Some programs may conflict with Roblox and cause the game to malfunction. Disable all unnecessary programs running in the background and check if this is causing the problem.
Viruses or Malware: Malware can cause application crashes and restart the computer. Check your system for viruses and malware using an antivirus program.
Incorrect graphics settings: Incorrect or excessive graphics settings in the game can lead to an overload of the graphics card and, as a result, restart the computer. Try lowering the graphics settings and see if this solves the problem.