My linux rhel 4.0 update 3 system becomes very slow when ever i open network connections it hangs and i need to restart it. what is this problem. I hope i will get the answer as soon as possible

thanku!

Please do not mark threads as urgent - this is a volunteer forum and no one question is more important than any other.

What do your logs show happening?

Also try posting here (CentOS is exactly the same as RHEL, with just trademarks removed)
http://www.centos.org/modules/newbb/index.php?cat=3

Hmmm, how urgent can it be when there is no follow-up after 4 hours?

We will also need to know what kind of network setup.

Do you mean:

Or:

So, does it go slow all of the time and then when you open network connections (several needed to cause this) it hangs. Or, does it behave normally until you open a network connection, then going so very slowly that the only thing that you can do is restart it?

Is this a server? What is it supposed to be doing? Does anything show up in your logs? Is it swapping when it goes very slowly? Maybe you have some process using a massive amount of cpu time. Is it sat on a high bandwidth network segment and running lots of network stuff? Have you misconfigured something in networking to send your network traffic in an infinite loop?

Does it carry on running long enough so that you can write a script logging stuff (say, vmstat output at a minimum, maybe ps output, depending on what seems to be happening) to give you a clue ('cos I'm sure that I don't have a clue without further information).

i am talking about desktop pc i dont know why pc becomes slow whenever i am trying to open network connection to change ip add and DNS add it becomes very busy and whole system becomes very slow down is it network problem i am using rhel 4.0 update 3.
thanku!

Search for the word "slow" in this link. Two possibilities are mentioned.

http://centos.org/docs/4/pdf/rhel-sag-en.pdf

Second Request: What is the network setup? For example:
cable modem or DSL?
Router?
fixed IP or DHCP?
Wireless or Ethernet?

Please provide as much detail as you can when asking questions like this.