I also had a similar experience. I swapped a used tiptronic into my 1st B5.5 Passat and about a week later it went nowhere when I left work. At that point I thought for sure I screwed something up or the trans was bad. I had it towed to a shop who told me it was just the CV joint. All in all, I was pretty relieved that was the problem even if I could have figured it out if I didn't jump to conclusions.