It almost sounds like a weblogic bug. Posting as an answer because I bet it will work:
Bring down your domain
Go to your domain_home/config folder and edit the config.xml file
Search for and change the following to your desired timeout:
<jta>
<timeout-seconds>30</timeout-seconds>
<completion-timeout-seconds>120</completion-timeout-seconds>
</jta>
See if you can bring your domain back up. If not, can you post a larger picture or copy/paste the stack trace? It is fairly hard to read. Also, which version of weblogic?