hi,
when u edit the c:\windows\hosts.sam in notepad there may be a few entries already present, added my some adware or spyware. u may have to remove them.
also u can add the what i mentioned earlier,
what the hosts file does that the dns lookups

the browser does not have to lookup if the entry is already present in t.

so the first line is mostly always

127.0.0.1 localhost.

that means the system ip address is 127.0.0.1 the local system(i think its a standard)

redirecting any address to 127.0.0.1 would get the local machine address and hence would be blocked.

eg. add the entry

127.0.0.1 www.amateurpages.com

now when u open the address www.amateurpages.com would redirect the browser to the local system and u will get no page returned. hence blocked. thats the idea.

also adding the entry

205.205.57.4 www.levelextreme.com

would also help because the browser looks up for the address in the hosts file when u type www.levelextreme.com and would not have to resolve the address as it gets it in the hosts file and fetches the page. this would open the sites faster.

hope this helps
suhas