The Mystery of Lost Internet Connection

About a year ago I got a call from a PC user completely perplexed by his sudden inability to connect to the internet. When I visited him he explained that he'd been using his PC quite happily earlier in the day, then went to use it later and found although the system seemed to be working in all other respects, it would not connect to the web.

His brother had a spare laptop so he borrowed that and found that it connected to the internet via the same wireless router he was trying to use his PC with. The line and wireless modem / router was obviously working fine, his PC box suddenly was barred from the internet. When I turned up I checked all the usual things, cable connection, no new hardware, no recently installed software and indeed I was able to connect my own MacBook and surf the web. Using an ethernet cable from the PC to the router made no difference, the PC had been thoroughly black balled from the web.

There was a complete lack of error messages, looking at Internet Explorer we were told the site had failed to reply, there was no internet connection and offering the chance to run a fault fixing wizard. My client had tried this many times and still the problem remained.

I took his PC back home with me, to try it on my network. No luck there either. Exactly the same, a stubborn inability to acknowledge the outside world. And I don't mind admitting, I had no idea of what was causing this and how to fix it. So keyed search terms into Google and reading various articles and posts in the search for an explanation. Nothing worked and very little apart from the loss of the internet connection seemed to fit with our symptoms. Until many, many hours into the search someone suggested investigation a file called TCPIP.SYS. That's a small file and all I did was take a copy of TCPIP.SYS from a working Windows XP system and use that to replace the copy on my clients machine.

Restarted the PC and a minute or two later we were on the web, surfing as Microsoft intended. Seconds to fix, hours to analyse. Days of feeling smug and of course one happy client.

I'd pretty much forgotten this until yesterday when a neighbour called me over. They have a Netgear wireless modem / router that allows his wife's PC and a laptop to connect to the internet but suddenly has barred his PC. The only event he could call to mind was a sudden spontaneous power down and restart after which his PC couldn't connect to the web. He too was puzzled, any site he tried to connect to gave him the same message, that the server wasn't responding, and that he had no internet connection when he could happily access all those sites from his wife's machine in the next room.

It took me a few minutes to remember my earlier experience but with the aid of my trusty USB memory stick we put a new copy of TCPIP.SYS onto his computer, rebooted, and away he went. The lesson is - if you have a sudden loss of internet connectivity for no simple reason, make sure you have a clean copy of TCPIP.SYS. or of course ring us on 01277 222 398.