Linguists call them real-word errors. They're very common in writing and spell checkers do nothing to protect against them.

I work on a free browser extension called After the Deadline. It picks a lot of this stuff up. It didn't pick up this particular example, next time I deploy an update to our service it will.

You may want to check it out, it works here on HN too: http://www.afterthedeadline.com

(as a note, I tend to make the same types of errors)

Actually I suspect that spelling checkers have made them more common. I know I see them a lot more often on the Web, and have been seeing them increasingly frequently over the last few years.

There are a few mild forms of dyxleia that cover thoses symptoms. For example, I cannot "sound out" words. I have to hear them before I say them. Makes for some funny times, thank god I have a great memory, or I'd look stupid all the time

I submitted a Wikipedia article on this very subject :-)

http://news.ycombinator.com/item?id=1477763

Apologies in advance for engaging in the clichéd 'submit a Wikipedia page' pattern!

malapropism

or "eggcorn", if the substituted term makes some kind of sense in context.

Malapropism.