Recently, I've noticed that my network connection often becomes unusable when doing an online update in Quicken 2010. When I say unusable, I mean my web browser stops working, pinging both local and internet hosts fails, etc, almost as if my network cable had been yanked. It seems that updating only one account doesn't trigger the behavior, just trying to update all accounts at once.
I've not been smart enough to note if this has been happening since I moved to Quicken 2010, but I'm sure it didn't happen with Quicken 2008, my previous version. I've seen some complaints on Quicken's website about QuickBooks 2010 having similar problems, but the solutions seem to involve changing QuickBooks settings which don't exist in Quicken, as far as I can tell.
I'm on a wired network. Running AVG 9, built-in Windows firewall. The OS is XP SP3.
I have noticed a similar symptom that network drives sometimes disconnect whenever there is heavy processing that causes the system to freeze for a moment. I get a notification bubble informing me that "DOMAIN is not available", and have to wait a minute or two before I can reconnect.