Files missing from Java cache

Hello,

My problematic application is a Webstart one. I install it on my computer and works fine for hours and suddenly i get this error message:

java.lang.IllegalArgumentException: input == null!
at javax.imageio.ImageIO.read(ImageIO.java:1362)

and my app freezes.

This tells me that the app is looking for an image file and cannot find it. I am 100% sure that this file has been requested before and was found.

The scenario above is a testimonial (accompanied by logs). I cannot reproduce it. But if I rename/delete that image file my app is freezing from the beginning, and I get the same error.

I know that the files needed for the app are stored (in some strange form) in the java cache when the jnlp is installed. So I am thinking that something happens the the java cache while the application runs.

Is there anything tricky about this java cache? Anyone seen this?

I know that this post doesn't really look like a SSCCE one, but there is no code example I could give, as I am almost sure it's not related to the code.