Elena, do you mean your spell check in Word? I had the most bizarre thing happen with my Word spell check the other day. I asked it to find the word "woods" because I thought I overused it and wanted to change some of those usages. Instead, it kept finding words like "what," "where" -- everything that had a "w" sound. I shut the program down, then restarted the computer, but it kept happening. I finally discovered it had somehow switched the options to "words that sound like," which I never noticed even existed as one of the choices. So...look at the options and see if the wrong thing is selected it.
Kris