internet connection problems

i work for a computer repair company and we have had problems on multiple computers lately with windows xp connecting to high speed internet connections. it seems to be something in windows xp as windows xp will claim in network connections and in ipconfig that it is connected to the internet but you are unable to browse in internet explorer. We have also tried browsing in mozilla firefox, and done simple things like try to get updates through NAV or Mcafee with no luck. has anyone else had this problem? We have found the only way that we have been able to fix this is to completely do a system restore or just format the drive and start over. As we have had a few customers have this problem and it has been tested on our cable connection which works with our shop computers just fine and still not working on the customers computer we are looking for a solution. any suggestions would be appreciated. also to mention this connections will occasionaly go to limited or no connectivity below is a list of what we have tried that has not helped.

ipconfig /renew
ipconfig /refresh
network connections repair option in windows xp
replacing network adapters
tried to ping websites - still no connection available
wireless connection
replaced cat 5 cable
tried different port on router
tried going direct into modem
rebuilt tcp/ip protocol
searched on the internet and forums for solutions
and i am sure we have tried other things i cannot think of right now.

thanks

john

 

I ran across something a few days ago that sounds similar to this. Did you notice if the xp machines with the problem had iTunes installed and if so, which version?

"The problem comes from a service called Bonjour that is installed along with iTunes 5 and Quicktime. This component is used for sharing music as explained here http://www.apple.com/macosx/features/bonjour/
Basically, once installed, it generates DNS conflict(s) and the outcome is that you are actually connected to your ISP but cannot browse.

It is supposed to be fixed in v 5.0.1 but there are some workarounds if this might be your problem.

Just a guess, but might not hurt checking.

Steve

 

i don't recall itunes being on these machines but its possible quicktime may have been. i may call a customer who is still having the problem and see if he has either of those installed. i could see it being a software item or even a windows update that is causing the problem as the last computer was reformatted a week before it started having the problem for the second time. it worked for around a week and then gave out again. i will ask if quicktime or itunes are installed on there. thankyou for the suggestion. any others would be appreciated.

john