Originally Posted by Retro Grouch
Check out the little screw that holds your bottom bracket cable guide. File that sucker smooth with the inside of the bottom bracket shell and see if that fixes it.
RG - I don't have a bottom bracket cable guide, so can't blame that.
Although, in general, that is always something to look for - I've encoutered such interferences in automotive and bicycling mechanics, as well as around the house.