[arch-general] pacman and keys

Hey, today I tried to update my system and got errors related to my pacman keys. As I have not been using my computer for a week I reinitialized the pacman key database and downloaded the arch linux keys with pacman-key --import archlinux. After that my libreoffice issues were solved, but now I get the following error: error: jre7-openjdk-headless: signature from "Guillaume ALAUX " is invalid :: File /var/cache/pacman/pkg/jre7-openjdk-headless-7.u55_2.4.7-1-i686.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)). Do you want to delete it? [Y/n] Y error: failed to commit transaction (invalid or corrupted package) Errors occurred, no packages were upgraded. Can someone help me out? Best regards, Heiko