You want all flaps and vents open and the beak open, unless it's blowing horizontal rain (in that case, the wind will provide plenty of air circulation even when the tent is partially closed). Closing up a single wall tent (or a double-wall, either) in still weather is a no-no.

Try to avoid camping in damp places (down in a hollow or close to water). If you can safely pitch under a live tree with no dead branches, do so. (Usually not feasible in the Rockies where most of the lodgepole pine is dead!)

Did you tighten your guylines just before going to bed? If that's not enough, some people use bungee cords.