Well that depends on many factors. If you would provide us with complete information, then someone here would be able to try to better answer the question for you.
No, best not to fiddle with the host file at all. If you are having DNS problems have you tried using OpenDNS? Its pretty easy to setup, change the DNS settings on your router and you use their distributed DNS system rather than your ISPs one.
Sounds like you've never called up an ISP support desk then :-) Experienced person is not how I would describe the average 1st line support person.
Jen
LOL agree with you there Jen when i ring up i can't understand what they saying.I have a majour technical problem and they go delete some cookies thats not going to help.There so dum i don't really know where you need to go for help when you need it.