Ransom virus pretending to be from the police

I have been trying to use the Norton Power Eraser tool to remove the Ransom program from my Desktop.  I seem to have no problem downloading the tool.  I hit a problem when I restart in safe mode with networking.  My Internet explorer wont stay online.  This is because I don't have a built in WiFi connection and use dongle instead (quite an old PC).  Can anybody advise me how to run the internet using my external dongle in the safe mode, as the tool seems to need to go online to run.  Unusual query, I know ,I hope someone can help.