Game automatically maximizing window during load screens

[weeeeeeeeeeeeeeeeb]

I have to play in windowed mode using the low effects setting since my computer is not the greatest.  Every time a load screen comes up, it maximizes the screen causing it to lag while it maximizes, and then again when i return it to its original size.  It's not affecting my gameplay at all;  it's just really annoying to deal with every time there's a load screen.