Hi,
I've changed my old P166 running 5.5 with a more 'up to date' dual P3-1000.
In this process I started with a clean 5.5 install on the P3 and all was running OK. Then I took my latest backup from the old P166 and restored it on the new machine. The new machine has a different network card so I had to change this on the consol.
After rebooting the new machine I can still access it through the consol and ssh (PuTTy) but I get a 'The connection was refused when attempting to contact ...' when trying to access the web and mail (IMAP) server.
PS: When the new box is running 5.5, I'll upgrade to 5.6 -> 6.0.1.