Did you delete a users folder?

Also you can go into the recycle bin select groups of files, delete them, until you get down to one that gives you the same message. Once you know what file is giving you the issue there are utilites that will let you delete a file when access is denied.

EMCO MoveOnBoot - Reviews and free EMCO MoveOnBoot downloads at Download.com

Also you could try to empty recycle bin after booting into safe mode. (F8 before windows startup)