Hi jchuzi I've got a iMac8.1 which is a OS X 10.5.8 version with 4GB 667Mhz RAM,I've reseated the RAM Modules & the computer is working fine have'nt had any problem within the last 4hrs so I guess the problems been solved, I must thank you for the info to have helped with the matter,as I'm still a learner of Mac,Thanks again Mapumalanga
