snap to path intersections doesn't always work

Sometimes (more often that not) I find that the "snap to path intersections" stops working. Say I have a circle and I want to put a text box at a specific point on the stroke of that circle. This is how I set it up:

Draw the circle (usually around the 0,0 point on the canvas). Then convert the circle to a path.
Generate a guide (usually vertical) and place the origin at 0,0.
Rotate the guide using the left click properties box so that it intersects the circle's stroke at the desired angle (say 30 degrees).
Generate a text box.
Make sure the "snap to path intersections" button on the toolbar is pressed. (The other necessary snapping buttons are already pressed).
Attempt to snap the text box bounding box center or edge to the intersection of the guide and circle stroke.

Sometimes it works and sometimes it doesn't. When it's not working, I've found that clicking on a different snapping button (say cusp node) will actually unclick the "patch to intersections" button as if they were radio buttons instead of separate toggles. If I go ahead and re-click the "path to intersections" button, then save, close, and reopen Inkscape, the button stays pressed and snapping works again.

I realize the button's name is snap to PATH and not guides, but I've seen the same behavior if I use a separate stroke generated by the pen tool instead of the guide.

If I'm somehow abusing this feature, or if there is a better way to do what I'm asking, I'm definitely open to ideas. A good deal of my designs are radial in nature and this snapping feature is absolutely wonderful when it's working :)

This is on a Win7 computer with an AMD processor. Inkscape version 0.91 r13725