It appears that Safari under Mac OS X 10.5 (Leopard) doesn't respond well to updated DNS (at least on my Macs). The penny only dropped while using Explorer in Parallels; Pprune worked fine, which meant that problem wasn't with my broadband supplier. Under Safari, all I got was the "Maintenance" page.
If anyone is having similar troubles under Leopard, go to Terminal and flush the DNS using the following command:
dscacheutil -flushcache
AppleMacster