According to my search results, certain Java updates caused this error in the past and then further updates have fixed it. That's very frustrating.
We have some options though:
1) Fallback to a previous Java version. This is not recommended due to security concerns.
2) Wait for a new Java update that fixes this problem, but that's quite inconvenient.
3) You can build Tomighty in your machine, but that requires some technical knowledge.
4) If you trust me, I can build Tomighty for you here in my machine and then send the package to you.