I have the same problem. Word keeps changing the proofing language to Spanish. The document is totally English. I change the settings to English in Review > Language > Set Proofing Language and also in Options > Language > Choose Editing Language. When I check again, it still says English in the default for Editing, Display and Help Languages, but whenever I run spell checking, the language is Spanish. I've tried to reset it multiple times, even restarting Word, but it doesn't stick! I am running Windows 7 64-bit and Office Professional Plus 2010, Word