Wanted to post this to save others my pain!

Ran into a major problem with a 98SE Laptop and XP Pro networking. Stopped working altogether. I could ping the laptop, but the laptop could not ping XP Pro. Updated the laptop to XP Home (was going to anyway).

Still same problem no matter how many times the Network Wizard was run.

A colleague at work had the same problem with his wireless setup.

We finally traced it to the requirement that the Guest user needs to be setup on XP Pro. I had deleted the Guest user since I set my wife and son up as the other users on the XP Pro box. This was the problem.

It was solved by updating the registry:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
ForcedGuest = 0.
This problem is not documented in Microsoft’s knowledge base or on any of the networking forums.

Both my colleague and I are developers and he is more network savvy than I am. If we couldn’t figure this out right away, most users would be up the creek.

As a footnote, the upgrade to XP from WIN98SE was smooth. I ran the upgrade advisor and eliminated any hardware and software problems that were detected. The laptop is a DELL Inspiron 3500, Celeron 366, recently upgraded to 10gig and 192meg memory. Starts up and shuts down faster than WIN98SE. Programs seem to runner better.