Okay, a number of people have found the latest firmware to be flakey, i have reverted to a firmware on my BEFSR41 of about 12 months ago.
You may want to try the same :pp
For some reason the latest firmwares seem slow and buggy. The particular problem I was having is that every 2 or 3 days the router would stop, no reason, it just stopped working. Damn annoying

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I emailed linksys about this and they actually told me to revert to the previous version of firmware ( bizarre ! ) but it worked.
Hope this helps a little more