Halo Trial-Really Weird Problem~Help!

Well, ive had Halo Trial for a while now, and really enjoy playing it (better players then on FV), and recently i just noticed when lets say im going forward crouching, and then i look left(Im still holding crouch and forward), and while looking to the left, my mouse goes really slow even though i moved it fast! Then, if i keep spinning the mouse, the game compensates and goes slow mouse movements then really fast twitches!

Its starting to get annoying. If that is too confusing this might help. If i hold too many keys on the keyboard at the same time, my mouse moves slow. But, this only happens in games. The only other game this happened was Jedi Knight 2: Jedi Outcast.

 

Anyone?