What do you mean by "the computer segfaults"? Do you get a kernel panic? Does the halt(8) program itself segfault?
** Changed in: acpi (Ubuntu)
Sourcepackagename: acpi => linux-source-2.6.15
Binarypackagename: acpi => None
Status: Unconfirmed => Needs Info
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Laptop segfaults when shut down
https://launchpad.net/malone/bugs/32175