NJ: same here, I can join SETI.USA on Primaboinca at will. Wonder what was going on? Maybe try a different computer / browser? Also maybe try detaching and reataching...
You will get pretty good credits on Primaboinca. On my rigs very comparable to AndrOINC.

Also, might want to check the AQUA sub-project we were discussing in the Team Only forum. I'm running a test on that right now.