we experience problems with Java 7 web start when the web server (Apache) delivers content compressed (gzip).
It seems that jnlp files cannot be read by Java 7 web start when delivered compressed.
The web start window shows only unreadable text where the content of the jnlp file should be shown and the exception is:
"Launch File Error: The following required field is missing from the launch file: <jnlp>".
The problem occurs on 32 and 64 bit Windows XP up to 7 (we didn't try on Linux/Mac) and only if the according jnlp file was not loaded before using Java 6 web start.
We have changed the default behaviour of the web server to deliver jnlp files only uncompressed.
This seems to solve the problem.
Does anyone experience similar problems?