I have spent hours (literally around 10) thinking I was messing things up, but tonight I created a project (I have 6 restarts now) just so I could send it to you for show and tell.
I have been creating shapes and lines. I am doing all the "duh stuff" like making sure I have all my points connected, hitting the space bar etc. I have some layers that will not create shapes, or once they do they will not show in the preview window. I label them that they don't work, and then when I go back before I make any changes at all they start working, or if I select them with the make shape selection box they work the second time. I then label these that they didn't work the first but worked the second time. I go around a third time they won't show even though they should still be working from the last time... it's random. And no I am not messing up the view option (eyeballs).
I even have one layer that is rendering lines that aren't there. So far this layer hasn't been random.
All these problems started when I started making hair strips (like you do in 3d programs).
1) Make a line with 8 points (or so)
2) Copy Paste this line 5 times.
3) Space the lines out from each other evenly
sorta like this:
. _____ . _____ . _____ ._____ . _____ .
. _____ . _____ . _____ ._____ . _____ .
. _____ . _____ . _____ ._____ . _____ .
. _____ . _____ . _____ ._____ . _____ .
4) Connect the end points on the left side (eg. point A0 to B0, then B0 to C0 then C0 to D0).
5) I then do the same thing to the right side.
6) Selction box the entire assembly with MakeShape . It highlights red. Sometimes it tries to do a fill (checkerbox) sometimes not (just lines).
7) Hit the space bar.

9) I hae one layer that almost never works. Even if I just take the rectangle or circle.
I am baffled, tired, and want to quit.
I'll be ok after a couple of days though.
I was so pissed off!!! I went and ran 8 miles before I posted on here.