Hardware problem?

My Internet connection dies if my laptop's on for too long.

Reader Ann writes:

My connection to the Internet (cable) goes dead if I leave my laptop on without using it for some time. The error message says "ARP cache will not clear" when I try to refresh the connection. I have tried it with both a wireless and Local Area Network connection, but both exhibit the same problems. My OS is Windows XP SP2 and I have all manner of security in place. Any help will be appreciated! Tried to read MS help page re:asp but is too nerded for me. ~ Ann

First off, a definition: the ARP (address resolution protocol) cache saves IP addresses for faster loading, ironically enough. Windows supposedly clears the ARP cache automatically every few minutes or so, but if for some reason it doesn't, your ARP cache can fill up and you can then no longer connect. That's what I think is happening in this situation.

Assuming that your network is set up fine - and it sounds like it! - there are a couple of things you could try to sort the problem.

• First you need to check if your routing and remote services are disabled (which should be the default setting in XP Home).
• To check, go to 
  Start | Control panel | Performance and maintenance (skip this if you're in classic view). 
• Now go to: 
  Administrative tools | Computer management.
• Click on Services and applications in the right hand column, and then Services again in the right hand column.
• Scroll down the right section of the subsequent window until you find routing and remote services and click to select.
• In the middle of the new window that opens select disabled from the drop down menu if it's not selected already. Now just click all the OK buttons necessary to back out of the control panel configuration.

That should work!

If you're still having problems, you could try the following command to tell your computer to delete your ARP cache automatically every five minutes.

• First off, open a command prompt by choosing Start | Run. Now type cmd and click OK.
• After the > sign where you see the blinking cursor copy and paste the following command:
  
  

  SCHTASKS /CREATE /SC MINUTE /MO 5 /TN ARPFLUSH /TR C:\WINNT\system32\netsh\interface\ip\delete\arpcache

Note: this is the command for Windows XP Home edition. If you are using Windows XP Pro you might need to change the "C:\WINNT\system32\" portion of the command to "C:\windows\system32"

If Windows is installed in a drive other than default Drive C: you will need to change the "C" to the letter of the drive in which windows is installed.

• Press Enter.
• You will be asked for your user login password as a security measure: either enter it, or, if you don't use a login password (which I recommend you do) then just press Enter again to skip this stage.
• Hopefully it says SUCCESS after that. 
• Now you can close the command prompt window, and that should have done the trick, at least until the next time you restart your computer.

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