Do not install Lightroom 1.4
Lightroom 1.3.1 was fine. Now there is a problem on import if converting to dng. Also on export, the time is not correct.
Yes there is an issue (Windows platform) when converting to DNG on import or from within the library. The same problem breaks existing DNG files when the Update DNG Preview and Metadata command is used.
Yes a bug report has been submitted.
Until it's resolved you would be advised not to convert files to DNG with Lightroom and don't update existing DNG previews.
If you prefer to use DNG my advice would be to go by to 1.3.1 now rather than wait for a fix, otherwise you're only get yourself into more difficulties.
You can download Lightroom 1.3.1 from
[link] Systems based on Windows XP SP2.
source - Adobe forums