There are few tools I would say that I use *every* day. This is one of them.ERR.exe is a tool I use all the time to look up error codes. When someone gives me an error code, the first thing I do is toss it in err so I know what I'm looking at. For example:C:\tools>err 8402# for decimal 8402 / hex 0x20d2 : SQL_8402_severity_16 sql_err# The data type of the '%s' must be '%s'. '%s' is not# allowed. ERROR_DS_CANT_CACHE_CLASS winerror.h# The class could not be cached.# 2 matches found for "8402"Note that it doesn't just look in a single .h....it looks in many at once! And not just Windows either. Very handy.You can find this gem here: http://www.microsoft.com/downloads/details.aspx?FamilyId=BE596899-7BB8-4208-B7FC-09E02A13696C&displaylang=enHappy ERRing!