Driving me nuts - browser keeps timing out despite fixes

Question

I have read through this and other forums in the hopes of finding a solution to my problem.  I am running Windows XP SP3, and with either Firefox or IE8 after 5-10 minutes my browser times out and won’t load any pages.  The only ways I can restore connectivity to the browser is to reboot or run the VPN software I use for work – once I establish a VPN connection there are no more time outs.  I thought that it might be a router or firewall problem, so I am now using opendns.org (both router and Windows fixes) and Malwarebytes for my protection software.  However, none of these changes has fixed the problem!  Is it possible that the Windows firewall is causing this?  I have been hesitant to turn it off.  I am hoping someone else has had this same problem and has a great solution they can suggest.
My thanks in advance for your help.
Pugrider
P.S. In the time it took me to write this post the server had timed out.  I rebooted any typed this is Word so I wouldn’t lose it…

Answer 1

Okay, I have a partial solution but one remaining question.
I am now convinced that the problem is my ethernet card is falling asleep and not waking up.  Searching the web revelaed that this is not an uncommon problem.  I received a response email from Actiontec, the maker of my FiOS router.  It indicated that the reason I was able to establish a VPN connection after my web browser had lost internet connectivity was that VPN acts as a pass through on their router.  However, the VPN software is clearly "waking up the ethernet card, because even after I disconnect the VPN connection my browser continues to work.  The Actiontec email suggested I take a look at the Windows and Ethernet card power management features, as they are notoriously flaky.  Here is what I have done to date:
Removed all traces of the McAfee anti-virus software.  Just running the Windows de-install won't remove all parts of this program.  Do a Google search and you will find a program from McAfee that removes the rest. 
I went into Control panel to Power Options and switched to "always on".  Make sure hibernation is not activated.
I went into Control panel to Network connections to check the configuration of my ethernet card (Intel(R) PRO/1000 GT Desktop Adapter).  Under the Power Management tab I turned off "reduce link speed during standby" and under Wake on LAN checked "wake on directed packet."  At first I turned everything off, but with some experiementation found that checking the "directed packet" option seemed to help with losing connectivity.  However, this may be incorrect.
I updated my BIOS from version A07 to A09.  Under Power Management the choices were S1 and S3.  S3 was active, so I switched to S1, and that seemed to help.  I could not find a way to turn off power management altogether or an "always on" option.  After reading a little on the internet S3 appears to be hibernation, whereas S1 is just the CPU powering down.  Again, I have no idea if this is correct or not.
I updated the drivers on my ethernet card.  This had no effect i could detect.
After all of that, my internet conection still times out after 10 minutes unless I establish a VPN connection and then disconnect it.  Once I do that the ethernet card stays awake and I have no other issues. So, can anyone tell me what setting I need to change or what else I can do to keep my ethernet card awake?  All suggestions are welcome.  Thanks.
Pugrider