The reason to monitor started last August when, for some reason, I widely exceeded my BT 10GB limit.
I went through all the obvious causes, even disabling Wifi, though I knew that it was secure.
I weeded out a number of programs that were excessively updating and controlled other programs that I needed to keep on the PC.
At that point, I installed Networx BW monitor and discovered tat the problem was due to Several unsuccessful re-attempts by Norton to execute a live update.
Just in case there was a nasty there that Noton could not see (Heaven forbid) I did a complete clean reinstall of W7 on a new Hard Disk drive but still experienced the same problems.
The olny thing that stopped me throwing the PC through the window was the knowledge that the windows were more expensive than the PC!
Eventually, I discovered that the NIC driver had issues and on updating that, the light appeared at the end of the tunnel.
At this stage, I would have been at the point where I could dispense with the NetWorx monitor exept, would you believe the BT's own usage monitor has now gone belly up, so for the time being, NetWorx stays, warts and all.
Incidently, earlier versions of NetWorx than 5.2.10, 64bit, run with W7, can cause intermittent Blue Screen of Death when the 'Ignore local traffic within the LAN' is selected in the main settings window.
Sorry to have gone on a bit but, some one else might benefit from this.
Best Wishes.
Harold H