Windows XP network connection lost

I am running Windows XP SP3 connected to Windows Small Busuiness Server 2003.
Ran disk cleanup and defrag on 3/11 night. On 3/12 morning I had an
exception error on defrag and shame on me for not writing down the error
message. I now have a red shield saying I am not protected, please turn on
firewall. My firewall is controlled by the server under group policies and
showing "on" on the server. After further searching, we had a Symantec
Antivirus scan that shows it had been running since 3/3. We have called
Symantec and fixed that problem. After going to my network connections,
there is nothing there and it will not allow me to set up a new one. We only
have 1 antivirus program on this Windows XP computer.

PLEASE HELP!
--
Lori