I'm desperate!

My desktop has been grinding away painfully sssllloooww for the past few days.
I run under vista.
Don't think I've loaded any new progs or done anything dramatic lately..
But for no discernible reason, the disk light shows a lot of traffic.
And the TBB icon confirms that a vast amount of data is being UPloaded.
Task manager shows no progs running, and I'm not clever enough to interpret the process tab.
Thought it might be Carbonite, so have suspended that.
Have just done a complete Kaspersky check, which shows no cause for alarm.
What to do?
I'd appreciate your thoughts please!

I'd disconnect it from the internet (if possible) until you find out what's going wrong. Perhaps you are now part of an e-mail spam bot. I'd reinstall Vista.

ensure you have clicked on show all users - might show something else running

On the Performance tab of Task Manager - there is a "Resource Monitor" button, which will launch Resource Monitor - it will show list of applications accessing network. Might give a few pointers

Try running SUPERAntiSpware (free) in SAFE mode disconnected from the internet followed by Malwarebytes again in SAFE mode and disconnected from the internet to see if there are any nasties.

Make sure they are both updated before dropping the connection to the internet.

Thanks guys for your thoughts, which I will gratefully pursue.

Regarding re-installing vista, this might be the finally deciding impetus for me to kick it into touch!

prevxcsi.com is a free lightweight malware scanner that will give you a second opinion, it will fix some of the things it finds for free.

0.9.6.4 and later of tbbmeter (upgrades out there now) has under its Statistics menu a list of IP addresses visited with amount of data going to them.

I'd suggest clear list, wait a few seconds and once you see the suspect activity you should get a list of IP addresses which can then be resolved and this may give a clue as to what is happening.

Future upgrades will hopefully link back to processes/tell you which ports etc