Hi so.. i got a student version of Solidworks2021 and have been using it a bit.. tried doing some work today but i encountered a really weird visual bug, where when i went in to draw a sketch line, every line i went through would like extend and stay and make my line basically dissapear with the mess that is created in seconds.. any ideas on how to fix/what to do? 
I provided an image of what it looks like...

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