Hi, for some new users it might be too difficult to download a fresh hostslist, so lets try this:
 
Start Xolox and go into Menu -> Tools -> Preferences
Then enter 'Gnutellahost': public.bearshare.net  
'port' goes into next input box: 6436 
Click "Add ", you'll see a message "New host added", close the preferences and wait a minute. Does it help? You can do this whenever you have a connect error. 
PS: here are more hosts caches. Enter name and port as above, do not enter the ':' (it's only a seperator): 
connect1.gnutellanet.com:6346 
connect2.gnutellanet.com:6346 
connect3.gnutellanet.com:6346 
connect4.gnutellanet.com:6346 
gnutella.hostscache.com:6346 
gnotella.fileflash.com:6346 
router.limewire.com:6346
gnutella.hostscache.com:6346 
gnet2.ath.cx:6346  
PS: some more links 
http://www.gnutella.co.uk/servers/ (current host caches list) 
http://gnutellaforums.com/showthread...t=hex+AND+edit