Hi again,
Apparently the problem with the current version of slime-complete-restore-window-configuration is somehow related to the use of bury-buffer. Instead of the hackish patch I sent earlier this version makes use of the present structure but calls the slime-close-buffer function instead, which basically does the same as the previous code but makes use of kill-buffer.
Another important issue is the use of the slime-completions-buffer-name variable instead of the hard coded "*Completions*".
Sorry for not paying closer attention to the code before sending the suggested patches to the list.
Tiago.