No Network Login Dialogue box Windows98

On a windows NT Domain no netware, have a user who received a virus w95.coke which was cleaned off but now does not get a login box for the network when booting 98SE. Tried removing network components, and re-adding but still just goes straight into 98SE. When we choose logoff it justs prompts for the windows login, not the network. Have selected Windows client login in the network properties. Any suggestions would be appreciated.