Location for XP : C:\WINDOWS\system32\drivers\etc
Right-click on Hosts File and open with Notepad to see entries.
Some info on subject if need to reset the Hosts file back to the default :
This was just a suggestion to check if hosts file changed by malware.
Info on Hosts (file)
Footnote : Don't get confuse between Hosts File & Svchost.exe
Svchost.exe is a generic host process name for services that run from dynamic-link libraries
You might have to seek help from Bleepingcomputer or SpywareHammer if nothing else worked.Out of suggestions here.
Have a nice Day