Can't modify sketch after creation

[WagglyFawn]

I made a sketch on the surface of an extrusion and now I can't modify the sketch. I can add more entities to it, but once that's done I can't select anything to modify it, such as moving, mirroring, or creating patterns. Is there a setting I need to be aware of? What's up???

Solidworks 2009

[shift1313]

Did you draw the sketch in 2d and project it onto a surface?

[JD Mather]

Can you reproduce this behavior in a new part?
Attach the part here.

[WagglyFawn]

update: I saved the file before I went home and the next day I opened it and everything worked as it should. I can't say what's going on, but if it happens again I'll attach and see if the problem exists for anyone who opens it.

[shift1313]

I have notices some problems before when my system needs a restart. Things like lines not showing up during creation(while dragging) but they show up after refreshing the screen or zooming in/out.