Tienes un problema de intercalacion.
Código sql:
Ver originalUPDATE tablaCH
SET Rst = Rst - 5
FROM tablaCH JOIN tablaMB ON tablaCH.Account = tablaMB.Account COLLATE Modern_Spanish_CS_AS
JOIN tablaNueva ON tablaNueva.Account = tablaMB.Account
WHERE tablaMB.Name = 'Vp' AND tablaMB.Stat = 1
AND tablaNUEVA.Vp = 0