When I dial in to my isp, my computer connects to isp but I cant browse the internet. It just says searching for yahoo.com for example and then nothing...I have been using this connection for almost a month with no problems at all..and I havent changed any configuration files etc. I have no problem connecting to internet using a win-doze pc using the same dns server, nameserver settings...please help!

Check if your DNS servers are on place. Also make sure that when you connect, when you run 'route' command from console, as root, there's a line beginning with 'default' and ending with 'ppp0'. If you don'thave it use
route del default
route add default ppp0

Do I do this before using kppp or wvdial?

bash: route: command not found
How do I solve this? also, My internet had no problems for 1 month...why am I having problems now?.. just wondering.

You can make it before and after. But 'after' is more important.

You need to be root. SO if you're logged as a normal user, first run 'su' and type root password.

Actually, I was root and it still returns that command not found. I got kppp working now..so I dont need wvdial. Again..why would a problem like this occur where its working fine and then one day its not, even though I never changed any settings/configuration ?

What does 'locate route' return? It should show you where's 'route'. If you get it, run it with full path.

It may be because of improper shutdown. Was there something like this?

its /sbin/route
what does it do, just for the future reference. I think improper shutdown might have happened, I dont really remember it though. Now my wvdial dials but it exits after connecting to isp server with the error code = 16. I got kppp working but I still would like to know how I could fix wvdial problem..
thanks

Heres my /sbin/route output:

Destination Gateway Genmask Flags Metric Ref Use Iface
tor58-19.sprint * 255.255.255.255 UH 0 0 0 ppp0
169.xxx.x.x * 255.255.0.0 U 0 0 0 lo
127.0.0.0 * 255.0.0.0 U 0 0 0 lo
default tor58-19.sprint 0.0.0.0 UG 0 0 0 ppp0
does it tell you anything about the problem?

Code 16 means
I (probably) means that options wvdial uses to estabilish the connection are not fully correct. During an incorrent shutdow the configuration may break. So you should check teh configuration (or just reconfigure wvdial from the beginning).

/sbin/route shows your routing table (it can be also used to modify it when given with correct paramaters). Routing table simply says which packet should go where (to which interface - NIC, modem etc). More info: man route.

Thanks for your reply Mara, I have tried reconfiguring wvdial (I even did a clean install od redhat again) but its still the same. Thanks again for your help

Look into /var/log/messages. It's a log file, among other things, pppd messages go there (every dialling program runs pppd), maybe there's somethong interesting.

1 12:46:52 localhost su(pam_unix)[2789]: session opened for user root by karamjeet(uid=500)
Aug 1 12:46:55 localhost kernel: This driver is not compatible with the installed modem codec.
Aug 1 12:46:55 localhost kernel: Please contact your modem provider for support.
Aug 1 12:47:29 localhost pppd[2819]: pppd 2.4.1 started by root, uid 0
Aug 1 12:47:29 localhost /etc/hotplug/net.agent: assuming ppp0 is already up
Aug 1 12:47:29 localhost pppd[2819]: Using interface ppp0
Aug 1 12:47:29 localhost pppd[2819]: Connect: ppp0 <--> /dev/ttySL0
Aug 1 12:47:35 localhost pppd[2819]: Hangup (SIGHUP)
Aug 1 12:47:35 localhost pppd[2819]: Modem hangup
Aug 1 12:47:35 localhost pppd[2819]: Connection terminated.
Aug 1 12:47:35 localhost pppd[2819]: Exit.
Aug 1 12:47:35 localhost /etc/hotplug/net.agent: NET unregister event not supported
Aug 1 12:47:35 localhost kernel: This driver is not compatible with the installed modem codec.
Aug 1 12:47:35 localhost kernel: Please contact your modem provider for support.
Aug 1 12:47:40 localhost kernel: This driver is not compatible with the installed modem codec.
Aug 1 12:47:40 localhost kernel: Please contact your modem provider for support.

Driver is not compatible? it used to work with wvdial and kppp- both of them and now its not compatible with wvdial? but is still compatible with kppp?

/dev/ttySL0? It should rather be /dev/ttyS0. Look into the program settings, it's probably a typo. OR, it may be a broken wvdial binary. Uninstall it and then install again from the installation CD.