Hello,
The default data folder is located at "C:\Users\<USERNAME>\AppData\Local\X1 Search"
there is a subfolder named "logs". In it there should be the crash.xml files, you can open the most recent one and post it's contents here.
Also you can submit a support case and provide us with more diagnostic information:
http://www.x1.com/support/x1_search_submit_case.html
Jogy