I checked the mentioned files, they are all available.
When I remove one of the dll I get a message about missing files, so I do not think this is the problem.
I created a helloworld program with cegcc, which works fine on the webdt.
Also the examples provided by the zlib and jpeg lib run fine.
However the example pngtest provided by libpng fails with the same message. So I assume the problem is in this library.
I added the following settings to the makefile....
MINGW_CCFLAGS="-DPNG_CONSOLE_IO_SUPPORTED -D_WIN32_IE=0x0400 -D_WIN32_WCE=0x0420" ALIGN="-falign-loops=2 -falign-functions=2
but no difference... continue to investigate... but help is appreciated.