Browsing on Some Computers on My Network

Two of the PCs on my home network lose their browsing connections after I log
onto the Internet. Both are configured with Windows XP SP 3. Both detect on
my network management software (Network Magic) as being connected and working
perfectly; however, when I open any browser (IE, Firefox, Google Chrome), I
initially connect to a Web page but then cannot continue browsing, as further
links do not work. After the initial page, I lose the link. Consistently, I
find that I can reboot the system and open the browser again, but the loss of
network connectivity persists.

In the case of one of the PCs, from the moment it was set up, it did not
browse properly. In the case of the other, it has worked until recently -
the past two weeks, and now behaves in the same manner as the other PC.

In both cases, the DHCP appeared to be working correctly. Network Magic
indicates that both computers are connected to my network and are functioning
properly. I have also verified that my IP addresses for all the systems in
my network are configured correctly. What do I need to do to get my
connectivity to stay active once I reboot these PCs?

I've looked in the archives, but none of the similar issues are similar
enough to help me solve my problem. Anyone have suggestions that will lead me
to a solution?

Thank you,
--
Michael D. Moore
"Respect Is Earned, Not Granted"