Intrusion Was Blocked

Over the past 2 weeks, I get this Norton window pop up all the time I am connected.

The attempts listed are;

MS RPCSS Attack (2)

MS RPC Server Service BO

MSRPC LSASS DS Oversized Request TCP

MSRPC Malicious LSASS DS Request BO

MSRPC Network DDE BO.

 

Norton tells me it has blocked them so I should be OK. But does Norton tell me when it lets one through??

 

Should I be concerned??  Why has it only started since (about) 15/01/09 ?

 

I update Norton & Microsoft, and scan regularly, but I have got to the stage where I unplug as soon as I have finished.

 

Confusion Reigns, can anyone help please?