How can I stop an ongoing sync process on my Desire?
I'd go to Settings -&gt; Accounts and sync and if you have an entry for Picasa, shut off sync for it.  If that doesn't work disable Background data in the same place, then go to your Media app or wherever you set up the sync and shut it off.  If you can't then you should go to Settings -&gt; Applications -&gt; All and clear the data for the relevant app(s).