The guild bank log logs every time someone deposits money, including each time they deposit money from quests.

Suggest:

Either trim the log down to report how much each person deposits into the bank (either voluntarily or through quest deposits) to a 24 hour period ("<player> has deposited 140 gold on 31 October 2010")

or

Remove logging of quest deposits, only logging voluntary contributions.

This is a bug and will be fixed in a future beta build.