Well, today for the first time in a while, I tried to rescynch my Ipod after adding some new music (and after updating to the current version of Media Center). As I now know-after reading this thread- the cache was missing from my ipod and it has to be rebuilt.
Rather than resynch right away, I am building a new cache. I did point the cache to the same folder as the old cache. But it is reconverting. Hopefully I wont end up with duplicat mp3 from my lossless wma files. About 1 1/2 hours into in, I am about 10% of the way through the conversions...and I hope when I am done, that Media Center will simply copy the converted files rather than reconvert them again. I was hoping when I started MC would simply copy the mp3s from my ipod rather than reconverting >4000 files to mp3 format.