I have seen that kind of *vanishing* behavior but only when working at the extreme levels of the Snap Grid (.001 setting) and try to zoom in. (Most often it seems with the Left View Window.)
Sometimes *Selecting All Objects* then *Fitting All Objects* will bring it back.
I normally work at a Snap Grid setting of .1 and Draw Grid of 1.
Don't know if this is same problem as yours ....
griff