You have only 4 GB RAM on an m1.medium instance, which is minimal for large data sets like yours. Most of the OOMs (OutOfMemoryError) before today are in the PermGen space so you will have to increase that, you probably have 512M at this time, increase it to 1024M. Starting today the OOMs are all in the heap space, which is what caused the server to freeze. You probably have only 2 GB maximum heap which is way to small to handle 11M row result sets. It looks like you will have to move to a larger EC2 instance with enough RAM to handle your needs.
Click on the XML tab and look at line 226, column 37 to see what the error might be. Another tip is to change the language from the default Groovy to Java, which sometimes gives a more detailed error giving you a better clue as to what's wrong. To change the language click on the main report node in the Report Inspector and click on the Language menu in the properties (near the bottom) and change the language to Java.
