Hi pieterse,
This seems to be a problem with the data on the Yahoo server. If you look here:
http://finance.yahoo.com/q/hp?s=^DJU+Historical+Prices
You'll see the "Close" price for ^DJU on 8/27/10 is showing as $302.46. This is out of the range of high/low, so it seems pretty clear it is an error. It appears to only be a problem with that one date. This is a problem that would have to be fixed by Yahoo.
On the volume issue, if you are retrieving from "Yahoo (Historical)" all the recent volumes are in the 4 billion range, as you can see on the link above. However, if you are retrieving from the regular "Yahoo" server, the volume is being reported lower. Right now it is showing the current volume on 8/30/10 to be around 3 million. Unfortunately, this inconsistency would also need to be fixed by Yahoo. Usually Yahoo and Yahoo (Historical) report the same volumes, but for some reason on this index they are off by a factor of 1,000 it appears. You may want to stick with using only one of these servers (Yahoo or Yahoo (Historical)), to keep the volumes consistent. Or, you could look at one of our other supported servers for updating this quote. You may also want to email Yahoo, and point out the problem with their inconsistent volume data.