I have a strange interaction with tramp and cygwin-mount (I think: Emacs: Tab completion of file name appends an extra i:\\cygwin). Because of this, I want to disable tramp. I\'
What a great question! If only because I was not aware of the function (eval-after-load file form) which will enable you to write code like the following and put it in your .emacs file:
(eval-after-load "tramp"
'(debug))
Which will, in brute force form, vomit a backtrace in your window and reveal the offending library.