Problem with Keys

I have a slight problem with my keys that I need to tlak to someone about, bah I just post it here, anway it used to be that when I pushed "w" and say "a" or "d" I would would go like diaginol or somehting, but now when I push "w" and then "a" I just go straight like it doesn't even register that I am pushin the "a" key, this is hard to explain kinda, like I can't go forawrd and strafe at the same time, it just goes straight forward instead of liek diagnol and i annoys the fuck out of me. SO basically heres hot it goes, I will push the w key and be running forward then I will push and hold the a key WHILE STILL Pushign and holding the w key and it will ahve no effect whereas it used to kind of go diagnol

Reinstalling is your best bet.