Try changing channels in the router, especially if your wireless adapter can detect neighbouring wifi networks. Move to a channel 5 stops from the strongest neighbour.
If no neighbours, experiment with channels anyway as the different freqencies they represent work better or worse in different environments.
If none of this makes sense, you need to read the manual for your router.
I recently bought a wireless card for my computer to connect to our home router. I installed the card and it has been working great! But recently my internet will randomly stop working. It will say that it could not connect with both Mozilla Firefox browser and Internet Explorer. Sometimes it works great and I can log on with no problem, then other times it won't let me at all, showing that it cannot connect. Also, sometimes when I have logged on with no problem it will later start acting ridiculously slow, then eventually it won't connect at all. I don't think it is my wireless connection because and my computer tells me that I have great connection and doesn't seem to have changed any, but I don't know. The computer will also not let me into my internet options. In my control panel, it shows an icon at the beginning of the list for internet options but but has no words under it and it will not let me open it. In my security center my internet option do not show up at all. If I need to to provide any additional information, I will! Just Please Help Me!!!