error generating png files

[VSD]

When running one of the following commands using lilypond windows native  
(2.6.0 or 2.7.6):

> lilypond.exe -f png test.ly
> lilypond.exe --png test.ly

I get the following log:

> Processing `C:/music/tst.ly'
> Parsing...
> Interpreting music... [8][10]
> Preprocessing graphical objects...Calculating line breaks...  
> [3][6][9][10]
> Calculating page breaks...
> Layout output to `tst.ps'...
> Converting to PNG...
> throw from within critical section.
> This application has requested the Runtime to terminate it in an unusual  
> way.
> Please contact the application's support team for more information.

and the png file is not generated, no matter which ly input file I use.

Perhaps am I doing something wrong?

Thanks,

Vincent