Nachi.worm virus

hi guys i have try to remove the nachi worm from my pc but it won’t work using blaster.fix or w32.welchia.fix tools from symantec
the error that i get
is the win32/Nachi.worm virus was detected in c:\winnt\system32\wins\dllhost.exe.o.avb

what should i do.. any suggestions please thank you