Internet sometimes doesn't work

Recently, when I'm in my university's library and trying to access the internet, I am unable to do so. Even if my wireless bars are all black and darkened, my internet doesn't seem to load, or it takes a long time to do so. Sometimes, I need to exit out of Safari and turn airport on/off a few times to get the internet access back on. Sometimes that doesn't work, and I just have to wait a while. Is this "normal"? Does this suggest something is wrong with my macbook pro's wireless card?

If that is the only location you're having issues, I would think it has more to do with the access point (e.g. the libraries wireless router) has too many people trying to access it simultaneously and overloading it's bandwidth.

I also have this problem, why dont know but sometimes when I connect to the internet in home wth my pc desktop, I cannot connect with my mac at the same time, I always have to disconnect then reconnect to internet, I wish I can handle this problem..

I also am having the same problem, both at school and at home. I never had this problem occur before, and it doesnt even happen to my other computers:-(

Mine always says, "failed to connect..." and it always asks me to reboot the modem/router...but I ignore it and restart firefox/safari and it starts working. I ignore it because it still happens again once i reboot it