I have just replaced my Streak (which had a hardware fault) but otherwise worked perfectly with a new one. The first thing I did was to upgrade it to Froyo/2.2.
I can't download anything from the market place. I had this problem last year when I changed from googlemail to gmail. I returned to my googlemail address, since when I have not had that problem - until now.
I have read that you have to log in to Talk, which I have never had to do before. It won't log in to Talk, coming up with a message 'Google Talk authentication failed'.
I can access my google mail/contacts/calendar with no problems.
Anyone know the solution to this?