Backdoor.Trojan with vista

Hi-

 

I am using Symantec Endpoint Protection and it recently found a Backdoor.Trojan on my computer which it can't remove.  The message provided is: SEP can't perform this action on 1 or more files because 1) the files have been moved or deleted 2) the file was found in an email message 3) you are trying to clean a compressed file in a container.

 

I have SEP version 11.0.4 and am running Vista  service pack 1.

 

The file location is C:\Windows\System32\gxvxcbnuxoiiqoltxpbmdvcttb.dll

 

 

 

Thanks in advance for the help