Security for Inbound Events

[DorisMay]

We changed our ISP to Sky a week ago and have McAfee installed. Trying to install some software on Monday I got a message that 'other people were logged on' . On investigation of events in McAfee I am getting hundreds of Inbound Events on the Internet, all from the same source IP quoting my administrator name and trying various ports and McAfee tells me that there has been an unsolicited attempt to get in. The same variation of IP address appears in my trusted ISP list when ever I log on which I then put in the Banned ISP list but then later appears again in the Trusted List. I have spoken to both Sky and McAfee who have not been a great lot of help. Am I being paronoid, am I under attack or am I worrying about nothing? Help!