wvdial and gnome-ppp both stopped working

[umair ubuntu]

i have installed intel536ep modem on my pc i am using ubuntu7.04
 it was working fine until today evening
later on when i tried to connect to net by using

> wvdial
>
fillowing message appears

umair at umair-desktop:~$ wvdial

--> WvDial: Internet dialer version 1.56
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Modem initialized.
--> Sending: ATDT13120002
--> Waiting for carrier.
ATDT13120002
CONNECT 42666
--> Carrier detected.Starting PPP immediately.
--> Starting pppd at Fri Jun 29 01:35:25 2007
--> Warning: Could not modify /etc/ppp/pap-secrets: Permission denied
--> --> PAP (Password Authentication Protocol) may be flaky.
--> Warning: Could not modify /etc/ppp/chap-secrets: Permission denied
--> --> CHAP (Challenge Handshake) may be flaky.
--> Pid of pppd: 6405
--> Using interface ppp0
--> Disconnecting at Fri Jun 29 01:35:26 2007

i have also tried connecting gnome ppp
it also seem to be in trouble it shows the following message

-> Ignoring malformed input line: ";Do NOT edit this file by hand!"
--> WvDial: Internet dialer version 1.56
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Modem initialized.
--> Sending: ATM1L1DT13120002
--> Waiting for carrier.
ATM1L1DT13120002
CONNECT 38666
--> Carrier detected.  Waiting for prompt.
--> Connected, but carrier signal lost!  Retrying...
--> Sending: ATM1L1DT13120002
--> Waiting for carrier.

what this means where is problem
plz help me
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