weird intermittent network problem

I've had 3 compters hooked up my my Linksys router and all 3 have been running fine for a long time. Recently, whenever my daughter tries to go on line with her computer, nothing works. IE, Outlook Express and AIM are all dead. If she reboots the computer, all of a sudden they all work. If the computer is turned off for a while, the connection doesn't work again.

When I try to open IE, Just the tool bar opens and then it just sits. When I try to open Outlook Express, just the opening splash screen appears and that's it. I can't close the splash screen. Even if I try to use Ctrl, Alt, Del, not even that screen will appear allowing me to close anything. There is obviously some sort of software problem when trying to use any internet connection. All other programs work fine.

When it's not working, if I check on the network connections, it shows that the LAN connection is working with no problems and is sending and receiving packets. It says that "Windows does not detect any problem with the connection". I click on the repair button, but to no avail.

I've checked and rechecked everything I can think of, but can't find any reason for this intermittent problem. Her computer is well maintained...defragged, no viruses, no spyware, no new software or hardware.

Anyone have any ideas as to what the problem can be? Any help would be appreciated. Thank you.

Intel P4 2800
Windows XP Home SP2
512 Mb Ram

 

How did you check for viruses? Have you ran HiJackThis to make sure that it is truly a "clean" system? From the sounds of what you described, is that there is defintely malware sitting on this machine due to the description of the problems that she is having.

 

She has AVG on her computer and it is updated daily. I ran AVG and it didn't detect anything. She also has Ad-Aware and Spybot and they didn't detect anything. I went to Trend Micro's site and had a full scan of her computer done (Virus, Traojan & Spyware) and it didn't detect anything either.

I guess the next step is to run hijack this and see what the problem really is.

 

Also, looking through the first part of your posting, this also leads me to believe that possibly ICS was set up, or some sort of Proxy.

 

Will check on the Proxy as well.

Thanks