Lose connectivity almost immediately after system boots

The system in question is a Compaq desktop running XP Home and Internet Explorer 7. I've lost connectivity (i.e. brings up 'this page cannot be displyed....' on all websites) within 1 - 2 minutes after the system boots.  In trying to troubleshoot this problem I started the system and went immediately to internet explorer and opened my home page which comes up but then freezes.  In network connections it says I'm connected. I know the modem is working fine as other computers are using it with no problem.  So far these are the things I've tried and the results:
1. Pinging various websites and to the modem comes back as 'Request timed out' (*see exception below)
2. Ipconfig /release and renew but nothing happens, the cursor goes to the next blank line and just sits there blinking.
3. Disabling the network connection works but when I go to enable it again, it can't do it & I have to reboot to get the connection back.
4. I tried to run sfc/ scannow but the window flashes on then off and nothing happens.
5. Disabling the firewall provided by my anti virus program (Windows firewall is already disabled) made no difference either.
One time a window flashed on and off so fast I didn't have time to read it but I did catch something about an SSL error but that's all the information I have on that one. I checked the internet options to make sure the SSL box was checked and it was.  
After one particular boot I was able to connect immediately but then lost the connection and I received a runtime error message with the following information in it: (I only received this one time)
Server Error in '/' Application.

Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

Details: To enable the details of this specific error message to be viewable on remote machines, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "Off".

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="Off"/>
    </system.web>
</configuration>       

Notes: The current error page you are seeing can be replaced by a custom error page by modifying the "defaultRedirect" attribute of the application's <customErrors> configuration tag to point to a custom error page URL.

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
    </system.web>
</configuration>       

I checked the event viewer and found a couple of items worth noting. Under the Application tab there were a couple of instances with the following description:
"A provider, OffProv 10, has been registered in the WMI namespace. Root\MSAPPS10, but did not specify the HostingModel property. This provider will be run using the LocalSystem account. This account is privileged and the provider may cause a security violation if it does not correctly impersonate user requests. Ensure that provider has been reviewed for security behavior and update the HostingModel property of the provider registration to an account with the least privileges possible for the required functionality. "
Under the System tab of the event viewer I found the following items with a red X:
Service Control Manager with this description: The following boot-start or system-start driver(s) failed to load: isStor, Intellde, Vialde
Also under the System tab but with a yellow exclamation point:
Dhcp: Your computer was not able to renew its address from the network (from the Dhcp server) for the Network card with Network address 0015F2913CA6. The following error occurred: The semaphone timeout period has expired. Your computer will continue to try and obtain an address on its own from the network address (DHCP) server.
*EXCEPTION I mentioned above: If I go immediately to the command prompt after booting up, I am able to successfully ping www.google.com but as soon as I try again, I've already lost my connection and it comes back as 'request timed out'.  
This all came on rather suddenly without any new hardware or other type of installations that I could have looked to for the cause. One more thing I should mention that seems odd is that one of the features of my anti virus program (Trend Micro Internet Security) is that it will report every 30 minutes or so, a list of computers connected to my network. This window still pops up and correctly identifies the other computers in my house. In order to do that would mean it is communicating with the modem yet I am not able to access the modem either by pinging or going into the settings.  
I'm not sure where to go from here and will be eagerly awaiting any suggestions from the Experts.