When should I use "corpuses" over "corpora"?

Solution 1:

The OED records corpora as the only plural, and that’s all I’ve ever seen in a linguistics context, or in any other for that matter. The entire OED has 71 citations that include corpora (admittedly with various meanings) and only one that includes corpuses. Corpus data also shows a far higher frequency of corpora over corpuses. Still, corpuses certainly exists, and with no apparent difference in meaning. If you’re conservative, use corpora. If you’re feeling adventurous, use corpuses.

Solution 2:

As with many 'correct' Latin terms, the rules for pluralising seem to be changing to adapt to the English language. If your use is formal, then stick with the corpora, but if it is a more casual usage, then the (technically incorrect, but accepted in many places) corpuses may be used without harm.

(BTW my spell checker complained about corpuses but didn't have a problem with corpora.)