adobe photoshop cs5 stroke problems

Dear Adobe Team,

We are using adobe Photoshop CS5 in our HP Workstation machine, but since we changed our OS in windows 7 we are facing stroke problems.

Like whenever we draw a straight stroke than it does not go straight it becomes curve type. Please find the below attached image of stroke.

We are using cintiq Pen display & HP z420 workstation.

So requesting you to kindly provide the solution ASAP