User login error when trying to access secured SQL Server database We have a username that was recently renamed from one username to another (think getting married). The Active Directory admin renamed the user because "it has always worked in the past". 

One vendor package we use uses the built-in MS SQL Server security. Each module has three groups:


xxView = View Only
xxUser = Add, Update rows (cannot delete)
xxAdmin = Delete rows


So we can add a person to one of these groups an they get the appropriate access. I don't have the actual error message in front of me anymore, but it said that they are not authorized to table CriticalVendorTable. It worked before the rename. The admin removed the person from each group and re-added them. Still no go. I even restarted the server and it still doesn't work. My best guess is that there is UUID (or unique id) somewhere that is causing problems.

The vendor's response is to delete the user and then re-add them. I have only had time to do some brief searching, but I found this page; AD User SID Mis-mapping. Would this be worth trying? Would it be better to just delete the user and recreate them?
Both options should work. The article you referrenced should deal with this exact scenario, but if the login is present for you to delete and re-add then go with that route. It is quicker and easier by far.