Internet temporary problem

Hello,
i have an Internet temporary problem . I am using a wireless connection. i was restart my computer 4 times,but im still could,nt get the internet connection. The signal is excellent and i do tracking with ping in a command prompt. there is a reply from server;

PING 202.167.0.155 (202.134.0.155) 56(84) bytes of data.
64 bytes from 202.167.0.155: icmp_seq=1 ttl=248 time=762 ms
64 bytes from 202.167.0.155: icmp_seq=2 ttl=248 time=897 ms
64 bytes from 202.167.0.155: icmp_seq=3 ttl=248 time=824 ms
64 bytes from 202.167.0.155: icmp_seq=4 ttl=248 time=564 ms
64 bytes from 202.167.0.155: icmp_seq=5 ttl=248 time=587 ms
64 bytes from 202.167.0.155: icmp_seq=6 ttl=248 time=751 ms
64 bytes from 202.167.0.155: icmp_seq=7 ttl=248 time=745 ms
64 bytes from 202.167.0.155: icmp_seq=8 ttl=248 time=673 ms
64 bytes from 202.167.0.155: icmp_seq=9 ttl=248 time=741 ms

as i know, if the result is like that, its mean the connection is oke, BUT i am still COULD'NT GET the Internet access. its different with the other PC, they get an internet connection.

In about 7 hour later, i am trying my computer again(wthout reboot my computer) to get the internet access, and i CAN connect to the internet

I Take this event two times in a week

its so dizzy for me..i dont know whats the problem????Please Help me........
Note : im using OS linux mint 6

Thx for advise