Hello Ian- welcome! :)
2 things come to mind:
1. Check all of your computers for viruses and spyware/malware/adware; these programs can cause the connection problems you're experiencing. Read through some of the other threads in this forum for instructions for downloading, installing, and running the following (free) spyware removal utilities:
HijackThis
Ad Aware
SpyBot Search & Destroy
SpywareBlaster
2. Check your security-related settings in your Internet Options control panel.Make sure your security levels aren't too restrictive, that you don't have unwanted entries in your "Restricted Sites", etc. You can try lowering the security levels temporarily and see if that helps; if not, my bet would be that it's a spyware-related problem.