Dell Dimension E520?

My dell Dimension E520 wont let me download or use AIM. When I try it says connection failed but on the taskbar I have a "very good connection". I can surf the internet fine. It actually lets me download IE7 but I cant use it. When I open it up it either says page not displayed or something about add ons. I have updated adobe and flash player. AIM says "connection failed" and Ares never connects. I looked to see if it was the firewall but thats not even turned on. Then I thought it was because this computer is connected wirelessly and it was a router setting but my laptop works fine with none of this nonsense. Does anyone have this problem?