Help please

hi

i recently installed a trial of 2003 server. configured
the dial up and pop3 e-mail accounts. everything worked
for two days but now i can connect to ISP but no browsing
or e-mails.So total dead internet even though im logged on
to the ISP servers.

2 problems :
1) My ISP has no idea how to configure 2003 (all they
could do was provide DNS addresses which didnt work and
made no real difference as I could connect before without
them)
2) I have no support from M$ as its a trial version

what i have done so far to try and correct the problem:
1)Reinstalled modem (modem working well)
2)Recreated Dial up
3) Tried every conectivity setting in the Dial up options
aswell as modem settings, changing ports, changing bmp
speed,port speed and receive and transmit buffer speeds to
try correct connection problems.Set to receive server
assigned IP DNS WINS etc all configured correctly.

I have Norton Internet Security with Firewall, tried
surfing with it turned off makes no difference.Have not
turned off the default 2003 firewall and have logged both
modem and ipfirewall, no errors that i can see.Have
queried modem with success logged so its working.

Any help please on this??
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I have subsequently reinstalled (upgraded) 2003 which
makes no difference. Still can dial up
but cant browse or retrieve e-mail. This is so frustrating
as I have only just installed 2003(to learn it)
It worked for over two days and now its dead. ISP say they
dont support ANY server OS.
Any help PLEASE!!!

Why would i buy this product if it cant last 4 days?