Is my modem broken?

Last few days ive been having internet problims. Over the weekend it would just come and go, when it came nothing worked at all, when it left everything worked perfectly. Powercycling my modem didint do anything, but all day monday it was fine. I cant explain why but i can say that one of my many powercycle attempts seems to have happened when my IP adress lease was being renewed, and i guess because i didint have the modem pluged in it didint renew that and i got a new one. Im not even sure if that can do anything, but that is the only thing i noticed as being different.

Then today i started having problims again. Only now the problims are all my upstream. I can be in a game and suddenly i cant do anything, but i can see people doing things. I can be chatting and i can get messages, but not send them. I can continue listening to internet radio stations, but i cant open websites.

Im not sure what could cause this.

1: Upload restrictions.
If youve been whoring the YAOI HENTAI torrents then your upload limit may have been reached, this means your ISP==FAIL==AIDS

2: your modem renews its IP lease every time it contacts the DHCP server. theres no way you can miss it by powarcycling because it would poll the DHCP for a new lease as soon as its up.

3: YOUR KAYBULZ ARE TEH SUX.
Signal to noise ratio = MASSIVE FAIL
Check your modems config/status page and find out if the SnR is through the roof.