I installed slackware64 13.0 on my Dell D630 laptop.
Recently I found a wierd network problem:

Sometimes, after couple of hours, I nearly cannot open
new websites. It takes so many time to open a page.
(I tried in firefox, lynx and konqueror.）

But some other connection still work, such as KRDC.

I tried nslookup and dig, they all works very
well, so the DNS is ok.

But ping works very slow with some url if I use the
domain name. And it runs very fast with the ip
of that url. So, maybe there is some problem with
the DNS, or something else.
ping result is:
1) ping by domain name
53 packets transmitted, 7 received, 86% packet loss, time 176196ms
rtt min/avg/max/mdev = 17.714/19.668/26.758/3.023 ms

2) ping by ip (same target)
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 19.052/22.237/25.422/3.185 ms

Restart the network with rc.inet1 cannot fix this
problem. Only I can do is reboot the computer.

I tried a lot to solve this problem. May be it's
a kernel(2.6.29.6) bug? Or the bug of my wireless card
driver(BCM 4311)? Or something else?
Who has the same problem, or knows the solution?

Thanks

Maybe you are having problems with your DNS server. Try setting a static DNS server other than your ISP's.

Thanks.
I don't think it's problem of the dns server.

Another computer with WinXP works well with the
same dns server. And after reboot, all works
well again.

When the problem happened, ping got a result as follow:
1) ping by domain name
53 packets transmitted, 7 received, 86% packet loss, time 176196ms
rtt min/avg/max/mdev = 17.714/19.668/26.758/3.023 ms

2) ping by ip (same target)
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 19.052/22.237/25.422/3.185 ms

Thanks

nslookup and dig are OK at resolving hostnames; ping is not ... what do /etc/resolv.conf and /etc/nsswitch.conf look like?

Thanks.
The /etc/resolv.conf is generated by DHCP, and the nsswitch.conf
is never edited before.

All these configure files are ok, because reboot can fix the
problem. (name server is same) And, the problem happens after
using normally couple of hours.

I believe there was a recent change in dhcpd versions from 13 to current. Maybe something in that?