Originally Posted by SCION
Did you install the basic Google apps as well? We had this issue on the rooted NOOKcolor some time. Try logging into a Google app besides Market. On the NOOKcolor we had to log into Google Talk. You can try clearing data and cache on the Market app.
No, I didn't install the basic maps. I did have "Maps" installed before, which used to work fine, but with the Market app installed it now insists on logging me in which doesn't work and therefore Maps no longer works. (BTW, I've since uninstalled Market and GSF since they weren't useful, and Maps now works again without the login requirement.)