Is it possible that 250ish is a previous "set-point" for you?

I ask because a friend of mine who started Atkins a year ago had a situation similar to what you're describing. The first 40 pounds that she lost came off steadily, and she was just thrilled. Then, when she hit 195 her weight started bouncing between 195 and 203. The fluctuations kept up for almost two months before she started losing again. She started getting pretty discouraged, but managed to stick to her eating plan because of she was so pleased with the results before her stall. One day she woke up, and had finally dropped to 193, and her losses started picking up pretty steadily again. A similar thing happened at around 175 for her, but it didn't last for as long.

In retrospect, she realized that before she had gained up to her high of ~240, she had held pretty steady at ~200 for almost two years. She now suspects that this is why she seemed "stuck" at 195-203 for so long.

Just a theory...