Occasionally lose connection to a share, but can still ping it.

Here is the problem I am having and would appreciate any input.

I have several W2K Server IIS machines in a cluster. I have another W2K
Server machine running my SQL 2000 database. I noticed that occasionally my
IIS machines will lose the ability to connect to the SQL machine. I happened
to catch one of these instances while I was on one of the IIS machines and
the following was happening:

1) my ASP pages could NOT see the SQL server service. I get an error stating
"SQL Server does not exist or access denied."

2) from the IIS machine I CANNOT connect to a share on the db. When I typed
in the path in the address bar I get an error stating "Windows cannot find
\\dbserver\sharefolder. Please check the spelling..."

3) from the cmd window I CAN successfully ping the database server by IP

4) from the cmd window I CAN successfully ping the database server by name

I wish I could have tried other things such as connecting to another IIS box
or any other computer on the network but this only occurs for a few minutes
and then all of the sudden everything is fine again. I first suspected
something was wrong w/ my DB server until I happened on this occurrence and
the other IIS boxes on the clusters were working fine.

All of the machines are running Windows 2000 server with the latest updates,
and nothing has been changed in several months on these machines except for
updates.

Any help with this matter or just some suggestions on where I should start
would be greatly appreciated.

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Thank you

James Requenez