My Norton cannot get rid of Backdoor.Tidserv.

Hi, new here and in need of some help, hence the name.

 

Anyway since the summer holidays I've been allowing my nieces and nephews to use my PC and recently it's been acting funny. Google searches go to random websites and never the right one, PC is running slower than usual lately and Norton Scanner is not working properly and is picking up this Backdoor.Tidserv virus thingy.

 

Can anyone help me/Knows anything about my problem?

 

Thanks

 

Need_Help.