After speaking to a friend I realized it was where I was trying to copy the arrays across instead of cloning them. (if you don't kno what this is try looking here:
http://geekswithblogs.net/dforhan/archive/2005/12/01/61852.aspx it helped me
alot) Albeit I had to completely change the biggerGrid method so it just turned it into a load of if and else ifs. This isnt ideal, so I would still be grateful to anyone who helped with this, because at the moment, part of my code looks like a donkey wrote it