spyware - istactivex.dll

I ran my weekly virus updates with Norton and they said I had a
file that was a problem :
istactivex.dll
Norton couldn't delete this file, I tried to delete it myself and couldn't. It's an adware file, I did an update of my Spybot-Search and destroy software and then ran the spybot and it didn't find this file to delete it.
I need some direction on this.
Thanks in advance.