Have you been through the performance tuning tips in the best practices guide?
Most likely you just need a faster server - if you bought it a few years ago it probably needs updating to keep up with the new load.
Oh, and doing a group scan from the menu in sbadmin will find all those missing machine entries caused by the slow group updates.
Hi Thanks for the reply, i guess you mean the tune up tips mentioned in this post? I will give them a go and also the group scan.
Many thanks for the advise
Thats worked a treat for the missing machines