It seems that you're using an unsigned integer to represent your coordinates. When you decrement an unsigned integer, such as 0, instead of getting -1, you get the highest possible value the integer can represent.

In fact, if you're getting 32 thousand, you're probably getting errors related to the comparison of integers -- you're probably representing your paddle coordinates with unsigned integers while your mouse coordinates are signed, or maybe the other way around. I'm guessing your paddle coordinates are rolling over from 0 to 65535 and then getting decremented 32 thousand times ... or something like that.