Google Translate

Google Translate works quite well. Occasionally it does some weird things. For instance, it translates (from Spanish)

No me acuerdo bien cómo me aparecìa.

to

I do not remember exactly how I appeared.

That is exactly what I'd expect it to say. However, when I change it by one word, 

No me acuerdo muy bien cómo me aparecìa. 

I get

I remember very well how I appeared.

rather than

I do not remember very well how I appeared.

If you change the initial verb to a synonym, it's correct. I.e.,

No recuerdo muy bien cómo me aparecìa.

becomes

I do not remember very well how I appeared.

I assume it's an error in Google Translate rather than me missing the subtleties of the Spanish language. Yet it seems like such a weird thing to get wrong. I'd really like to get into natural language parsing one day. Maybe then I'd discover the answer.