fuzzythinker: Okay so got a call and an email with a usage report from Vodafone which basically explains the amounts of data trafficked up and down and when.

Johnr will no doubt be pleased to hear the report came back saying that Voda had got their numbers right!

In any case the report has enabled us to narrow down the issue to my partners MacBookPro.

Whatsmore the traffic has mostly gone into uploading.

Using the process described bellow (thanks to RunningMan) we checked out what was currently happening on the networking usage front.

RunningMan:

kingjj: [snip] Not sure where the equivalent would be on your partners Mac.

Activity Monitor, in the Utilities folder (inside Applications folder).

Click on the network tab and it will tell you what's happening.

Even now seems to be quite a few packets going both up and down. I'm not to sure what this should be normally but my hunch that the issue hasn't gone away, but as this machine has been off most of the time traffic through the router has returned to normal.

What I need to do now is home in on where the problem is coming from within the machine and make sure it doesn't happen again.

Unfortunately at this point my partner started freaking out that her precious Mac could 'have a virus' so machine has been shut down and going to have to deal with the problem when she is out.

in order to do that I need to know:

Is this a Malware / Spyware / unknown nasty causing the high data traffic, and how to check that for a Mac?

Could it be part of an OS or app update process?

What other possibilities might their be and how to identify / eliminate (Mac users please help!) (note pretty sure its not Iphoto).

Cheers