Strange problem with internet connection

I had a very strangely looking problem with my internet connection. I was not able to browse any web page, although I was able to ping them. I was not even able to browse files in other computers in my local network... It was even more strange that I wasn't able to browse web after a certain period of time since disabling the network connection and reconnecting to AP - this always solved the problem temporarily.

However, I tried to find a permanent solution, and, mainly, find out what is the source of the problem. After reading a few discussions on the internet, I found one that was very similar to what I was experiencing, tried it and it worked.

Are you wondering what was wrong? Encryption. It seems that under some circumstances, there might be a problem with wireless connection using WEP encryption - the AP simply doesn't allow TCP packages to go through. I changed the encryption to WPA2 (AES), and the problem is gone :-)