MR modem problems, catastrophic failure

When I put XP on my computer everything went fine until it got to the internet bit at the end of the setup where soemoen else went to fast and i missed it. So when i try to connect using XP it says 633 error, something else is using the port. My port is com 3 and when i looked nothing was using it. So i couldn't get on the net to use the help, and the troubleshooter wasn't helping. And when i found out that MR modem wasn't going to work on this i wanted to get some help. SO i put ME back on and went on the net. Does anyone think they can help, i need to know if i can use my MR modem AND use XP, without them both conflicting with each other. Or have I done something wrong!

Plus, when i go to the my computer and open any of the internet folders, it says catastrophic failure!

 

modem

Is your MR Modem a modem riser card? What mainboard here?
Need to more about this system.....