Backend changes? phpESP admin authentication prob

Hi. I am running phpESP 1.6.1 on both cognac+fin and strange+sylvester. I was wondering if last week any changes were made to the installation of php or mySQL. My installations on cognac+fin no longer authenticate, which the developers tell me might be a mysql 4.1 hash table bug. Problem is that my installations on cognac+sylvester are working fine. I am assuming that the shell servers are all identical (strange and cognac) as well as the database servers (fin and sylvester). So I am just grabbing in the dark. Anything that I may have missed WRT to changes between May 13 and May 20? Thanks,