dimension problem

hello all

whenever i dimension in a sketch , juste after i select either the two points or the object , the pointer disappears and moves at the bottom left of the screen .

i have to bring it back to the center to be able to position my dimension . this makes dimensioning a real problem .  

it happens only on my pc at the workplace either with solidworks 2008  and 2009.  this pc runs windows xp with an nvidia quadro fx 3450/4000  . 

the problem doesnt happen on my coworkers pc  nor on my home pc 

any idea what is wrong ?

thanks in advance

SolidworksSketching