I doubt it's Opus doing this. You likely have a shell extension that is trying to contact the internet for some reason (which is odd and worth investigating).
Shell extensions are DLLs which run within the DOpus.exe (or Explorer.exe) process so when they run it looks like Opus is doing it.
If you turn on Preferences, Miscellaneous, Windows Integration, Hide Windows items on file context menus (shift overrides) then the connection attempts should stop. If that's the case then you've confirmed that it is a 3rd party shell extension rather than something built into Opus itself.
Tracking down which shell extension it is can be a pain, though. The stuff in this tip might help:
[Tip: Organise and Speed-Up Context Menus)
If you're familiar with editing the registry then you can find the GUIDs for some of the shell extensions and add them back to Opus one-by-one using the tip, but there are some handlers which aren't as easy to find. Worth a try, though.
It might also be worth running an anti-spyware tool to see if it detects anything on your machine. There could be a legitimate reason for a shell extension to connect to the internet (maybe it's doing an update check, although doing it every time someone uses their context menus is a bit silly) like this but it could also be spyware.