What is lsass doing?

I've noticed over the past couple of days that the icon indicating network activity is staying pretty much solid, even when nothing is going on - when I check processes, I see that there is indeed communications traffic going in/out, but don't know how to determine what's causing it. I do see a ton of i/o in the entry for lsass.exe - and it seems to be the only process that's doing any i/o right now. Is that normal? How could I find out who is doing the communications activity? tnx,

 

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I'm using AVG Internet Security Suite (anti-virus, firewall, spyware, etc) but I don't see any way to monitor all traffic - the log just shows packets that were blocked. I did, however, determine that it's LiveMessenger that's causing all the i/o - TONS of reads/writes. When I kill LiveMessenger, everything settles down, and when I start it back up, I get solid communications activity. I've never seen this before, assume it's not normal - what should I do now?
thx!

 

I may have to try that - Live Messenger has never caused any problems, tho, and we use it in the office to keep in touch with other associates. This has just started, and I've shut down LiveMessenger because of the excessive (and constant) communications i/o - can't figure out what it's doing -