Broadband usage nearing limit after only 1 week ?

[#1]

Yes since I switched off my new PC and reverted to my old one the activity has ceased.
and as I mentioned previously, looking at my TBQM history, it started up/downloading 4GB per day for the first 4 hrs the PC was switched on each day since Monday. After doing the restore it started doing it again today so I switched it off before I exceed my 40GB limit.
Norton IS is installed on both PCs and is updated automatically, both are saying they are up to date.
MS updates only accounted for a fraction of the usage.
I have downloaded Networx & TCPView which I intend to install on the offending PC once I have disconnected it from the internet.
But I will try the full Norton scan first as you suggested. I also have MS Security Essentials installed, but neither one has so far reported any issues.
Although I do not use Norton Web Backup, I do use DropBox, Google Drive & Sky Drive, but as they are also installed on my old PC, which works fine, I don't think it can be any of them.
The only programs that have updated during the last week appear to be iTunes & an HP Printer app.

[#2]

OK full NIS scan - Nothing Found
Run TCPView and reconnected to internet.
Immediately Appleiedav.exe started downloading data
By selecting to end the appleiedav.exe process the data transfer stopped !
Appleiedav.exe appears to be part of Apple's iCloud Control Panel which was recently updated, but as yet do not know what it was doing
Possibly some sort of backup ?

[#3]

As you've figured out, the majority of the usage is showing as upload. I've included an image showing yesterday's usage breakdown by hour:

[#4]

see https://discussions.apple.com/message/23710128 regarding Appleiedav.exe

[#5]

Chris thanks for that, I don't suppose you can identify the IP address the data was being sent to ?
I'm confident it was Apple, but I would like it confirmed before I complain to them about it.
chenks76 - yes that link confirms what I suspected - by selecting to sync my IE Bookmarks in the iCloud control panel, it has been sending 4GB of data to Apple every day without my knowledge !
This is an unprecedented amount of data for Apple to send without any warnings !
So can I demand compensation from Apple for using up a whole months PN allowance in just 8 days ?

[#6]

A couple of weeks ago I treated a computer with boot sector virus cidox.b http://community.plus.net/forum/index.php/topic,130346.0.html .  This virus was not detected by most security software and was responsible for very heavy internet usage.

[#7]

Hi Dave,
When I read...

Quote from: Dave

The only programs that have updated during the last week appear to be iTunes & an HP Printer app.

I immediately thought "I bet the new version of iTunes has got iCloud configured by default".  I bet you will not find that your music library has gone off your PC and is now stored in the cloud.  It can be a real pain in the bum.  SWMBO was not astute when she updates iTunes and now she has a devil of a job accessing her music.
Hope you can get it sorted.
...I'm really grateful for seeing this as I'm too about to upgrade iTunes! 
Kevin

[#8]

Wow & Holy Smoke - Who gave iTunes permission to move my music ?
Fortunately as I have only just built this PC, I had not got around to moving any of my Music from my old PC's iTunes folder, so there is nothing in iTunes to move as yet - phew !
But thanks for the heads up, as I definitely don't want another 30GBytes of music being uploaded, especially not right now as thanks to Apple I am at my monthly usage limit after only a week.
Also I do have all my music backed up on my NAS, so even if it did disappear I could easily restore it, but I will now have to see how to stop Apple moving it - I did think it was only when you subscribed to Apple's new service that your music was held in the cloud ? Apple must have moved the goal posts again