You can halt a script by pressing esc (windows) or command-Period (mac) as long as:
- Allow user abort is not used in the script to disable this.
- The script isn't "hung" on a single step (such as a perform find that triggers indexing a field and the index is corrupted.)
Scripts that perform finds often pause for user input. Do you see a button that says "continue" in your status area at the top of your screen?
Is this script run from a script trigger or when the file is opened? (Maybe the trigger selected is performing the script all over again each time the script completes.)
Can you post your script?