Hidden Files

I am XP SP2 user... I just installed Norton IS 2010 and joined to community...

 

I could not show my hidden files...  Changing in 'folder options' means notting...

 

I was thinking that this is because of an virus infection and I made full check up by NIS but no still no result...

 

Is this because of a trojan or virus??..

 

Would you please help me: how can I turned show hidden files option??..

 

Kayhan