small cursor in game

hi sorry for all the questions today my game is bugging out hard so when i load the game the cursor is the right size but after 10 minutes of playing it sort of backs out of the game and then re-enters the game at the same point of where i was but the only thing that is different is the cursor is really small  anybody else experienced this before  the game runs perfectly apart from this   but the cursor is only that size in the game on my PC is ok