I’m having the same problem. I’ve uninstalled WordPress and reinstalled at least five times to start from scratch and I still have the same problem.
I can see the 2 default themes (1.6 and classic) just fine (and switch between them) but when I try to add a new theme (I’ve tried a number of them from different sources, all the same result) and activate it, everything goes white, including the admin page. I then have to uninstall and reinstall all over again.
I assume something that is corrupted isn’t getting removed when I uninstall but haven’t a clue as to how to fix it.
Pretty frustrating. WordPress 1.6 never gave me problems and themes uploaded fine.
Help?