Try 64bit java (you may need to get JRE from the JDK download page) and uninstall all old versions
Also try launching the main .jar file of lawena with the command "java -jar -Xmx1024m [jar file]" (navigate to the folder then type cmd in the address bar to open a command line there) just to make sure.the max heap size is getting set (I don't trust the java control center tbh)