Conversion from string to type 'Date' is not valid

Hi

Im receiving a strange error Error Message: Conversion from string "15/08/2010 22:21:35" to type 'Date' is not valid.

I know this is generally down to cultural date formats etc, however the reason this is strange is it just randomly occured twice in the last week, the website has been running since october and nothing has changed,

The error constantly occured until the IIS was reset and recompilled the site, its been running fine since, however im just trying to figure out what could cause such an error to occur.

I've narrowed it down to a line of code which is:

bktime = DReader.Item("Bktime").ToString

bktime = Year(CDate(bktime)) & "-" & fmt(Month(CDate(bktime)), 2) & "-" & fmt(Day(CDate(bktime)), 2)


Has anyone else encountered this randomly occuring an ...