I am also newbie and started with hourglass example and encountered exactly the same problem as described:
- Bob Lang ( boblang99 ) - 2012-01-03 - Null Pointer Exception when saving file - ID: 3469240
- Warren ( warren867 ) - 2012-08-03 - Some textures and materials appear not to save - ID: 3554131
The problem is that I can NOT save the changes made after Uniform material was entered. The temp file size is 0 and before that step everything was fine and that is why it seems not to be Windows permissions problem. As Bob Lang described there appears Null Pointer Exception when saving file. Thanks for any advice and support.