I removed the shield from the start-up programs and added Zone Alarm as my
firewall. I have not had any problems since. I don't know what the shield
does (I did add the IP address of the DSN & DCPH in the shield, but it did
not help), but I seem to be the one causes the problem.

Very often I've discovered that when a firewall is causing a problem on the
system, disabling it using the prescribed methods (by the software
manufacturer) doesn't solve the problem because the firewall is still
running albeit in a "disabled mode" right from startup. I've often
recommended that when people have problems with browsing similar to what you
are having that they completely uninstall the firewall program, and see what
happens. 9 times out of 10, that solves the problem. Usually the same
software can be reinstalled and work perfectly fine (until the next time it
gets corrupted). In your case, it seems that removing it from startup and
installing another firewall program seems to have acheived the same net
effect. Um... excuse the pun.