My Tamron 18-270mm is giving me all kinds of headaches on my D90. It will on and off cause a camera-lockup - "F--" (which to me is abbrev for "F--KED!") It is an issue with the electrical contacts. It appeared soon after I bought it. I brought it to servicing. And without much explanation or demo'ing the problem, the guy who took over my lens for servicing already know what is the problem - i.e., a problem that occurs often.
After servicing, it worked well for a while... and now sliding back to square one I don't have time to bring it to Upper Changi Road North for repair yet... hope to do so before my one-year warranty runs out.