I am having the same problem.  I have two companies with payroll accounts that have different EINs.  I was getting the same error code on both when trying to update payroll info.  I have both companies set up for automatic updates.  I did a manual update even though there were no new updates available.  I was then able to update the info for one of the companies but still gettiong the 400001 error code when I try to update the other.  The quality of customer service provided by Intuit Quickbooks has declined dreadfully.  I hope this issue is resolved soon.