Selection/Deselection Problem

Hi all

i am facing a problen in pro Engineer.the problem is that i have installed ProE W5.When i select a plane,or edge or skecth or dimension line then it doesnot deselects with a single click outsid the edge or plane etc just like in other people Pcs.i mean when i just move the mouse pointer over the outline of a plane it highlights in cyan colours as yours but it dehighlights after a long time as compared to other systems and during this the system remains hang.....i have 1.8Ghz core 2 duo,2.2Gb ram and 1 Gb Nvidia graphics card in my Pc.can any one please to remove this headache....