I had similar issue.
I had an user on SQl as abc(name changed), I deleted the user and without rebooting I created a user with same name as "abc", and tried login to SQL with abc credentials.
A connection was succesfulyl established with the server, but then an error
occured during the login process.
(provider: Shared Memeory Provoder, error: 0 - No Process is on the other end of the pipe.)Microsoft SQL server error:233
I created another user xyz and tried login with same xyz and I was able to login.
Then I rebooted the machine and tested with abc account and I was able to login.
Now I deleted xyz and created xyz again, now I was not able to login with xyz with same error.
It seems when we deleted a user SQL Server requires a reboot, if we want to create user with same name again.