Debian上网不正常，问题很奇怪

scuwolf

系统配置是 debian3.1r0,2.6.8-2-386
通过pppoe拨号上网
症状是这样子的 ：
pon adsl连上网以后，开始的时候上网是正常的，大概过了一分钟以后，网页就不能打开了
，FireFox出现以下错误信息
The connection was reset
The connection to the server was reset while the page was loading.
# The site could be temporarily unavailable or too busy. Try again in a few
    moments.

#   If you are unable to load any pages, check your computer's network
    connection.

#   If your computer or network is protected by a firewall or proxy, make sure
    that Firefox is permitted to access the Web.

用用Mozilla Web Browser则提示：the document have no data

下面是ip信息。
ppp0      Link encapoint-to-Point Protocol
          inet addr:220.167.40.129  P-t-P:220.167.40.1  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1492  Metric:1
          RX packets:353 errors:0 dropped:0 overruns:0 frame:0
          TX packets:568 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:3
          RX bytes:51624 (50.4 KiB)  TX bytes:27543 (26.8 KiB)