In trying to get a faster boot I opened "Manage System Services' and, without being quite sure of what I was doing, stopped a few things that I thought were unnecessary.
These included ATD, XFS, NSCD, PORTRESERVE, SSHD AND VB stuff. I sure got a faster boot but, when I opened Firefox 18, I found it had gone back to Firefox 17. The same with Thunderbird which had reverted from 17.0.2 to 17.0.1. (Bad move.
Nothing very serious though - some of my bookmarks in FF and a few emails in TB had gone.
I replaced all the stuff I had stopped but was srill stuck with the earlier versions of FF and TB.
This is a bit trivial but left me wondering which system services I don't need . I have three machines but no LAN and no peripherals at all so there must be some stuff I don't need? Cups for instance....