We have a 3005 here at the main branch, and 2 PIX 506's at remote locations, with a Lan-to-Lan VPN between each of the remote PIX'es (each on DSL) to the concentrator (on a T1).  We have had several issues with the connections dropping randomly, sometimes several times per day.  There have also been times that we have had to reboot either the PIX, the 3005, or both to get the connection to re-establish.  What I can gather from the logs, is that the connection is dropping, and the concentrator does not realize that the connection is gone.  As soon as we log out the conection via the admin client, it comes right back up.  Most of the time this works, however, like I said, there have been times that we've had to reboot the PIX and/or the Concentrator.  Any ideas would be GREATLY appreciated, as I have already contacted Cisco regarding this, and their best suggestion was "upgrade the IOS".  We are running the latest IOS on each product, and have tried almost everything I can think of.

make sure all the timers, ike and ipsec match.  The defaults on the pix and concentrator differ and seems to cause this issue if not all set to the same.

Have you had any domain browsing problems with the 3005??
I am having problems with 3015..

have setup wins/dns etc and can domain login/email etc
but no microsoft browsing...