High Memory Usage in IIS (w3wp.exe)

About a week ago we noticed some problems occurring on our site. We were
getting "Out of Memeory" errors, DLLs get untrapped errors, and noticed that
the memory usage on our IIS boxes was extremely high. We added 2 more web
servers to alleviate the problems, and this has bought us some time. The
servers are all new servers running Win 2003, IIS 6, 2GB of RAM on 2, 4GB on
the others. We are seeing memory being used by w3wp get over 400MB on the
servers. In doing some preliminary tests I see what appears to be caching
occurring in memory, but no noticable objects being left open. I have
installed DebugDiag on both our QA envronment and now our Production
environment in an effort to see what is going on. Lastly, we are also seeing
CONNECTION_DROPPED DefaultAppPool in the HTTPERR logs which the MS site says
is "RESERVERD - NOT CURRENTLY USED".

Any help or guidance in determining/fixing the problems is greatly
appreciated.
--
Joshua Roth