Back Door Trojan won't delete!!!

For over a week or so now I have been scanning my computer even though it says there are no infected files, yet I still come up with a infected file named globalroot\systemroot\system32\. The description I was given was globalroot\systemroot\system32\gxvxcxmh....

It says its a backdoor trojan, but no mater how many times I scan it, it still appears. 

 

Can anyone help? And If anyone can, please please dumb it down and do it step by step because I get confused easily with computers :)

 

Thanks!