Problems with my custom rig.

Well I only just built my computer and I already have problems:( well 1. When I boot the pc up it doesn't display anything so I have to switch off and turn it on and it works! But it's really annoying. 2. When I boot up into windows 7 it works but the keyboard messes up and types all the wrong keys like when I turn caps of it types in caps and I can't use numbers and that stuff and also the mouse selects all of the files I select it.
Ps: got a psu 3days ago and the keyboard and mouse thing started happening

My specs:
Amd sempron 145 overclocked to 3.11GHZ from 2.8GHZ
Asrock n68 vs3 fx
Zalman zp plus mid towercase.