A lot of DSL modems actually have routing functionality that interferes with your actual router. They tend to use a PPOE setup, which means you have to tell your modem to not do PPOE and use the settings that it had to tell your router it's a PPOE connection, complete with the login user/pass and external IP address the modem was getting. I know that sounds complex, so maybe just google on that subject with some keywords and you'll likely find the steps for it.
The fact it comes up as a recommended program simply means it is still associated with that extension. XP Help and Support is your friend here. "To associate a file name extension with a file type Open Folder Options in Control Panel.