Why does the Zibo 737 LNAV have a problem staying on the flight path?

Question

When I fly the Zibo 737 the LNAV works perfectly fine for a good 5 min but then it starts to steer of path a little. How do I fix this problem of the LNAV not following the flight path?

Answer 1

Wind? and I don't know how to get 737's to adjust for wind and i've been looking for hours.