Partially Failing Lens

Back in May I mentioned how the mirror on my camera broke and I did the $5 MacGyver repair to fix it. Well, a few days ago I went for a quick mid-afternoon photo shoot and discovered that my 18-55mm lens is not acting up.

Anytime I'm zoomed between 18-24 mm, if I have the aperture set to anything other than wide open, the picture fails and the camera gets an error 99 and locks up until I power it down and back up. Not sure if this is a problem I can figure out how to fix. Might be time to look for a new lens.