There are a couple reasons why this could happen.

The most common reason is map optimizations in program memory. These optimisations do not clear from game to game and can build up eventually conflicting with each other. After every three games you should completely close Warcraft III and reload it to clear all optimisations.

For league play I recommend reloading Warcraft III after every game or remake.

Another reason is a corrupted Warcraft III installation. If you get regular critical errors you should uninstall and reinstall the game.

The third reason is the map itself. Some are not properly coded and they will critical error on a bad trigger.