problem with podcast files

I have an iPhone 3G. Over several months I stored about 15 podcasts. Last week I upgraded to 3.0, and after that all my podcasts have become inaccessible. Itunes still lists them as being on my phone, but they are grayed out. Can't play them, can't erase them. When I download a new podcast, Itunes shows it as available, but when I look for it on my phone, can't see it. I tried rebooting, but no luck.
Has anyone else had this issue? Any ideas on how to clean out these phantom stored podcasts which are probably there but inaccessible?

From the ipod options in iTunes, try un-checking all the broken podcasts, sync, then re-add the podcasts and sync again.

If that does not do the trick, I would try a factory restore. That would mean that any of your apps would loose their data/settings, but at least you would have a fully functional phone again.