This isn't the first time this has happened, and it isn't something I can prevent. As far as I am aware, It is a problem caused by bukkit 1.1 it causes a number of plugins to generate very large log files very quickly. This problem causes files to be reset to default (log, ban list, player rank). I have contacted the hosting company multiple times about this problem, the last response I received was, "We sincerely do expect this to no longer be a problem".
Thanks Temphas and Spongemd for posting on forums, I'll see what I can do about lost items, probably not much...

Sorry for the long response time.