What version of AOLserver are you running? This sounds suspiciously similar to problems I've had when using HTMLarea as a form input.
I was experiencing the same thing, because I automatically double-space after a period. For some reason, the two contiguous spaces produce these mysterious characters (although I was getting different characters than you). You can experiment by putting in a bunch of spaces in a row. Usually this will produce a number of these strange characters.
I originally reported and discussed the problem in this post: https://openacs.org/forums/message-view?message_id=127088
At the time I was using AOLserver 3.4.2, which apparently didn't have the patches to deal with various character set issues, but I have since had similar problems with AOLserver 4.
I've resorted to an extremely ugly workaround, but it does work as a brute force method. I use a procedure to map those particular characters into empty strings.
However, I've been unable to completely filter the characters out *before* inserting the text into the database. For some reason I have to pull the text back out, run the filter, and then re-insert it into the database.
It seems that on the first pass some of the characters get mapped into other artifact characters that are then successfully removed on the second pass. Like I said, it's UGLY, but it's the only thing I've been able to do to get it to work.
This is my current string mapping: [string map [list \201 {} \215 {} \217 {} \220 {} \235 {} \240 {} \255 {} \263 {} \302 {} \303 {} \305 {} \352 {} \601 {} \605 {} \617 {} \620 {} \635 {} \640 {} \655 {} \702 {} \703 {} \705 {}] $string]
I've had to add additional characters as they cropped up during editing, but at this point I haven't come across a new one in a while.
