NIS 2010 Intrusion Attempts!!!

I installed NIS 2010 about 2 months ago, and everything was great up until about a week ago.  All of a sudden I started getting a lot of intrusions attempts, MS RPCSS Attacks 2 and 3, all of which are considered to be "High Severity".  Norton says that it is blocking these attempts and no action is necessary.  However I am concerned as to what would happen if one of these attempts were to make it through.  I don't know what to do to stop this from happening anymore.  I have run scans constantly, both online and off.  I even ran a scan in "Safe Mode", and Norton doesn't find anything but some tracking cookies that are easily removed.  When I chatted with the tech support, all that was said was everything is fine but if you want we can scan your computer for $140!!! 

 

I am completely out of ideas, can someone please help me with this?!?!?!?