Do you, by any chance, have your language set to UK or British English?
I've had the same issue with every Ubuntu-based distro I've used. It doesn't seem to cause any problems other than the error messages you're seeing.
GA-965-DS3, Core 2 Quad 2.4GHz, 8GB DDR2, 2x1TB HDD, Linux Mint 11
Acer Aspire 5332, Pentium dual core 2.2GHz, 4GB DDR3, 500GB HDD, Linux Mint 11, Linux Mint Debian
Compaq CQ-60, Sempron 2.10GHz, 4GB DDR2, 120GB HDD, Tinycore 3.7rc2 (Minecraft server!)