When I try to start Act! 6.0 i get the following error box:
act.exe - Application Error "The instruction at 'ox0270431' referenced memory at 'oxbo2d8726'. The memory could not be 'read'.
A reinstall fixes it only for a few days.
Can you try your Act installer on another computer, and see if it starts failing after a few days? You can also try testing your memory through memtest86—your computer is basically complaining that there's something wrong with it.