The Microsoft error code lookup tool (which no Windows admin should be without) got updated today: http://www.microsoft.com/downloads/details.aspx?familyid=be596899-7bb8-4208-b7fc-09e02a13696c&displaylang=en&tm.
While it says it's for Exchange, it really covers Exchange, Windows and a number of other Microsoft products. You can plug an error code in and this tool will give you whatever definitions it finds in the headers compiled into it. If you've ever seen an event that says "the error code is in the data", or you get a message that "unknown error 0x80045500" has occurred and you have no idea what to do, this is where to start. I keep the binary in the path on my workstations. Here's a sample for one of the most common codes you'll see:
C:\Documents and Settings\Administrator>err c0000005# for hex 0xc0000005 / decimal -1073741819 :
STATUS_ACCESS_VIOLATION ntstatus.h
# The instruction at "0x%08lx" referenced memory at
# "0x%08lx". The memory could not be "%s".
USBD_STATUS_DEV_NOT_RESPONDING usb.h
# 2 matches found for "c0000005"
Generally speaking the correct result is the first one for this example. When you get more than one result though you'll have to look at the names of the header files (e.g. usb.h) and see which one makes sense.
I wonder what was really updated? The binary shows the same version/timestamp as the one I have been using for quite some time now.
C:\Admin\Util\Err>filever err.exe
--a-- W32i APP ENU 6.0.4011.0 shp 1,698,816 04-01-2004 err.exe