Eh, my TyTN got infected last weekend. Internet Sharing turned BT discovery on (was that even called for? I already paired my device with the PC anyway) and didn't switch it back off when I was using it as my DSL went down a few days before, and I was under the impression that it was off because I remember rolling my thumb over the "No" button on the sometimes dodgy touchscreen). I didn't know it was on and walked into a train. Later, I found a bunch of sent files on my phone, and apparently one must have made it through (another mistake: I forgot to lock the keypad and the screen when I put it into my pocket before boarding the train)- the phone started acting sluggish and randomly freezes up a few hours later.
I had to hard reset, and lost all my text messages and Opera bookmarks.
Lesson learnt: check the BT settings whenever one use a M$ app that uses BT, and always lock the phone when keeping it in one's pants pocket.
I will get an antivirus for it if a free one comes out. You can never trust a M$ product after all.