Keynote 1.1.1 has a longstanding issue where an inordinate number of previously saved presentations cannot be opened. There are a number of factors that can cause this problem:
Font culprits in some cases Anthony Carruthers, a poster to Apple's Discussion boards, reports that problematic fonts were at the root of the issue in his case:
"I remembered that fonts remain a confusing and troublesome issue even in Panther. So I opened Font Book and noticed that each time I tried to de-activate one of 2 OSX symbol fonts on my PowerBook Font Book would quit. It turns out that I was deactivating the Apple symbol.dfont (System/Library/Fonts folder) and leaving the Design Science MathType 5.0 symbol font active (/Library/Fonts folder). This crashed the Font Book app reproducibly. Deactivating the MathType symbol font (by dragging it to the desktop) and reactivating the Apple Symbol font (by dragging it back to the System/Library/Fonts folder (with authentication)) permitted Font Book to run and now permits me to run my older Keynote presentations."
Viewing package contents to delete problematic images, other media Sometimes, corrupt or mysteriously damaged elements of presentations can cause the files to be inaccessible.
In some cases this can be remedied by accessing the contextual menu for a presentation - either by holding the control key and clicking it, or using Mac OS X 10.3.x's "Action" button) and choosing "Show Package Contents" from the menu. Try removing images, movies, or other media that might be causing the issue.