I have windows XP home and have beed downloading the updates as notified. I have installed SP2 and i am using AVG free as my virus protection etc.
Recently though i have been unable to brouse any internet pages and just get the DNS error cannot find server page. Around the same time a message appreared on my screen "common client user session has encountered a problem and needs to close". The following information is attached to the message, ERROR SIGNATURE. APPVER 2.1.5.1, APPNAME:CCAP.exe, MODVER 0.0.0.0, offset 0192fd7d. None of which means anything to me?
My connection status tells me that i am connected, however when i click the internet button i go straight to the DNS error page.
I don't believe that i have changed any of my interet setting, my service provider is Tiscali but they do not seem to be much help!!
Any help would be greatly appriciated.

Ok... do me a quick favor... In the C:\WINDOWS\SYSTEM32\DRIVERS\ETC folder on your computer there will be a file named "hosts" open it with notepad and scroll to the bottom of the file. Are there a lot of ip addresses and websites listed in this file?

Sorry for delay this prob is on my home computer, I have checked the above (opening with notepad) but the only text is the example of how the ip addresses are listed.
Whilst in the system32 folder i noticed an error32 dat which was shown to be an adware that i cannot delete manaually??

Ok, then you are dealing with some spyware/malware/virii or such that likes to hijack the internet connection/browser. Try running spybot or adaware in safe mode and see what it will clean up. If it still can't delete some files, then that can be done on the command line with the attrib command. Let me know if you need more info on how to do that.

If you don't have the program called hijackthis, you should probably get it. You can find it several places by doing a google search for it. You can save a log file and then post it on the proper forum and someone will help you decipher it.

I will try the first suggestion, but i would like some info on what to do with the command line just in case.
Cheers

in the command prompt, type in

ipfconfig /all

and see what your IP Address is. If it's something other than 169.254.xxx.xxx, then you should be in okay shape. If it is not 169.254....., then try pinging what's listed as your default gateway. If you can ping that, then ping what's listed as the DNS servers. If you can get there, then try running ipconfig /flushdns, perhaps.

Also, try disabling any firewalls. I don't suspect any malware personally, but gefflong could be on some track I'm not aware of. But, in a situation like this, I generally start performing TCP/IP troubleshooting, which usually leads me to the likely source of the issue. That error you provided sounds like a firewall issue, so your firewall would be a good place to start.