Yes, SQL Server does seem to "sticky-cache" a lot of the AD security information for a long time. Rebooting your server is probably the recommended way to fix that.
Alternatively, you could try removing the Login from SQL Server and then re-adding it. That might work, but it might also be more trouble than it's worth.
[font="Times New Roman"]-- RBarryYoung[/font], [font="Times New Roman"] (302)375-0451[/font] blog: MovingSQL.com, Twitter: @RBarryYoung[font="Arial Black"]
Proactive Performance Solutions, Inc. [/font][font="Verdana"] "Performance is our middle name."[/font]