Rogers @home's whole ISP network design. I believe:
1. The only way rogers has control is the hostname of a user computer.
2. The not so dynamic IP is totally decided by your hostname.
3. If anyone has a good hostname and a rogers modem, theny can connect.
4. There're malicious geeks out there doing things like killing your box and then use your hostname and connection.
5. there're many reasons for that. They can do certain things that they don't want to do with their own IP.
Of course this is just an assumption. So in order to protect yourself, have a dedicated line, which you can get from DSL.
On the other hand, may I ask the OS of your gateway PC and your firewall software? I also suspect certain OS works less stable with @home...