Apparently, it goes back to my English instructions in school. Back then, it was taught that two spaces come after a period, exclamation point, and colon when typing. According to the websites I just looked out, that's common convention now. However, what's going on is, my blogging software interprets the first space fine, but then puts in the code for a space for the second. That's a little irritating. I *like* the double-space rule (though I've been informed that with computers and fonts and all sorts of other things I didn't necessarily understand (or care about), the double-space is no longer needed at the end of a sentence. But, to me, having that there makes the page easier to read.
I've learned typing in the seventh grade, back in '87/'88. That's ~20 years of unlearning I'd have to do to go to a single-space convention. I like Scribefire a lot, but to me, not being able to properly interpret double-spaces takes a lot away from it. Maybe I can find a solution to it.