Workstation Service Terminated With Service-specific Error 2250
First of all, 1000 thanks to Trefenwynd for the sanity-saving advice about that crummy little "mrxsmb.sys" file missing from the XP C:\Windows\System32\Drivers folder.
I have been working on this nightmare for over 20 hours and 2 days now, and was just about to give up and call MS Tech Support (never a pleasant task) when I stumbled across this solution which hit the nail precisely on its head.
I actually joined the Forum just to say thanks and alert everybody to a closely-related problem which ultimately brought me here:
For totally unknown reasons (except maybe uninstalling Norton SystemWorks and Personal Firewall, prior to the installation of Windows OneCare Live) the Windows Workstation Service suddenly just would not start; it had been working perfectly up to that time.
I searched the MS Knowledge Base as well as the Internet, double-checked all the pertinent Registry entries and the corresponding files (save for the one mentioned above) with a known-good computer, and could find
nothing wrong or out-of-place until I ran across this post.
Anyway, anybody having this sort of problem should also check out this article:
http://www.jasonhartman.net/2005/01/problem-starting-server-and.html
The part about the accounting software may or may not apply to your case; if it doesn't, just scroll on down for a variety of solutions.
The main thing is that between the two of these articles you should be able to get back up and running in no time; it's outrageous that there isn't more technical information in the MS Knowledge Base about this situation, as obviously many, many people are experiencing the problem, with virtually no resources available to help solve it.
I just hope this helps others as much as it helped me.
Good luck!