iv added some more block erupters but when i start the client all i keep getting is selftest error's, can anyone shed any light on this? iv check all drivers and all my ports and everything seem fine in both.

many reasons why.
most reasons are poor quality hubs... so what hubs do you have.
other reasons are raspberry pi only likes certain hubs..
more reasons too many hubs on a slow set up. I run 96 sticks on 1 pc but everything is high quality.
if you send a pm or reply here with details on your setup i can help