I get the following error when i try to upgrade to the most recent build and my forums are down in the meantime

Upgrade Aborted
current build: 11023
{"status":"success","type":"upgrade","section":11048,"response":"Build upgrade section 11048 executing. Status: success 
","error":""}

what version were you upgrading from?

can you check the browser console?  in particular the server response for the ajax install.. will likely reveal another plugin outputting data corrupting the response...  wp super cache is a good one for doing this too...