What do you mean unable to access internet but internet speed is slow?
What Antivirus are you using? This virus may stop it from updating.
It is infecting your hosts file blocking access to websites.Download Avast! Antivirus
and run a boot time scan after installing it.
You could also run an online scan. The best online scanners will be blocked by the virus but Bitdefender online scan
should work (requires IE).