Im pretty sure i understand what you mean. A "change address" has fractions of bitcoins that just hang there?
A change address is described here:
https://en.bitcoin.it/wiki/Change it is important to note your wallet GUI does not display the change addresses in the address book. (the real world ramifications are back up your wallet.dat regularly)
It is not a problem when you send BTC, but if it comes out of a change address you need to follow Klestin advice here: Here
https://bitcointalk.org/index.php?topic=195052.msg2078386#msg2078386 to find the send address.