Question : Serious and strange ISSUE with my LAN

Pulling My Hair off the HEAD.....

GRRRRRRRRRRRRRR

6 Months, NO Solution.........

What we have.

NetGear Router (4Port)
Switch (Around 30 Ports)
Verizon DSL Modem.
23 Computers

Router is Connect to the Dsl Modem (Has a satatic IP Address). And Router connects itself to the Switch and Switch Goes to the Ports in the Wall.

LAN works fine with the DSL.

* Following problem started to happen *

DSL Connection goes up and Down, I though maybe its the router problem, I changed the router NO LUCK.
Then I though maybe its Switch I changed it NO LUCK.
Then I replaced some (Not ALL) network Cables and DSL modem as well NO LUCK.

now what Can  I do to fix my Network Droping Problem?
DSL just stops responding for few seconds and then comes back to normal.
AOL Instant Messenger keeps Signing in and Signing off because of DSL connection.

Can anyone please give me TIPs on how to solve this problem? or two find out what exactaly is causing this problem.
By the way i also Changed the DSL provider to make sure its not the provider but NO LUCK.

THANK YOU
God Bless you.

Answer : Serious and strange ISSUE with my LAN

I have a suggestion that's easier for you to digest. If it's possible, pull out all computers from the network. Leave 1 computer connected. Do some stuff that'll create network traffic, surfing, emails, MSN Messenger, etc. After half an hour or so, plug in the next PC, do the same stuff, surf the net, check emails, etc. And this goes on, until you either hit on the problem or not. If you hit on the problem, remove all other PCs, leaving the last PC connected that caused the problem to see if it happens again. Your first PC might be the one that has a problem so check a few PCs first.

Furthermore, by leaving one "working" PC connected to the Internet, you can verify if your DSL connection is giving you any problems. After going through the above steps, you should be able to isolate whether the problem is on the ISP or on the LAN.

Of cuz, this is more of a no-brainer way of solving the problem, but it'll help you start-off with troubleshooting straight away without having to read too much into protocol analyzers. No guarantees that the above menthod will track down your problem though, but I thought it'll be worth a shot.