XP Internet Connection lost, then explorer.exe crashes

My computer keeps losing its internet connection. The internet connection in the system tray stops responding to left or right clicks. About five minutes after the connection is lost explorer.exe crashes - The icons on the taskbar including start and system tray stop working, explorer windows won't work. I can close explorer.exe as a process in Task Manager and restart it and it will work but I can't connect to the internet again. To get the internet back I have to restart. When I shutdown the computer hangs at Saving Your Settings.

I previously had the same problem and fixed it using a system restore. Unfortunately, not one of my System Restore points is working at the moment.

The internet connection loss seems to be related to the amount of bandwidth I am using. If I have a lot of YouTube videos downloading or if I use a p2p software like BBC iPlayer, then I will have it cutting out. The problem is annoying but not quite bad enough for me to want to go through the trauma of reinstalling windows esp. if it is going to come back in a couple of months time.

So far I have tried to turn of all unnecessary background programs; running programs to reset my winsock, lsp and tcp/ip settings. I did have other programs crashing at the same time: ctfmon.exe (Office Alternate Inputs) and ccApp.exe (Norton Antivirus). I have stopped the parts of those programs that were causing problems.

I also have a problem that may be unrelated. When I start the computer I get a found new hardware "VIA Master Bus IDE Controller". I have never managed to install this hardware or remove this message even with a windows reinstall. This error came up after I replaced the motherboard.

I have an old system: Win XP + SP2, AMD 1500+, 512MB RAM

Any help or advice would be greatly appreciated.

 

I do keep my system in pretty good condition. That CCleaner program is great. I haven't done a non-Microsoft Defrag yet. All the other stuff didn't resolve the problems though.

I have noticed that if I unhook the DSL cable from the modem I still get the computer crashing. So even without being connected to the internet but having programs making demands on the internet (esp. BBC iPlayer) explorer is crashing.

 

The defrag didn't do it either. I followed the whole Basic Computer Maintanence Guide. I do most of what it suggests regularly anyway. I have tried a bunch of Spyware and Virus detection software. I have gone over HijackThis logs, looked through the registry, looked through the services. The problem was occuring before I started using BBC iPlayer and still occurs if I remove it from both the startup list and services list. The internet connection bug didn't come up at a time when I was changing a lot of things on my computer. I think Norton is the most likely candidate to be causing trouble. I have put the settings down to minimal running but it is still an annoying program. Pity AVG isn't free anymore. My ISP give me Norton for free.

I was hoping it was something people might have previously encountered. I think it must just be a bug in Windows XP. I am sure there must be a setting somewhere I could change to get rid of it but I think I may have to reinstall Windows. That is likely to take more time than I lose to the occasional internet crashes though. I am planning to get a new computer in the next six months so I'm not sure it is worth the effort.