Bit of an odd one

Bamber19

Every so often I seem to hit somthing on my keyboard when i'm on this forum and suddenly the text and spacing will have changed. (for example, and I'm assuming it will look fine to you, in that last sentence the word "will" looks more like this "w ill") It's not the text size option on internet explorer and it doesn't look normal. In the past i've just went back to another page and it's sorted itself but it's stayed around this time (for now at least) In addition the lines between some boards have disappeared. I realise it's probably something to do with page spacing but can anyone tell me firstly how to sort it and secondly what it is i'm hitting to cause it. (i'm assuming i'm hitting ctrl+ a letter, it's always down in the left hand side of the keyboard when this happens)