Essentially, the redraw problem is most probably the graphic card. Make sure it's not onboard. Otherwise, your openGL support may be wrong. I had to buy a new card. If you buy a new card, since this is not gaming and will not require a full blown card, any good recent card should do.
What version of bobcad are you using?
seems there was a problem with 19.3 or so for printing. Make sure you have 19.4.4.
I would expect a software at version 19 to be free from that kind of bugs, not so... well... still like it tough...
Para
Paraman, Parabeast, Paramachine, Parameter.
The many in one and the one in the many.