FULL PRODUCT VERSION :
java version "1.5.0_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_04-b05)
Java HotSpot(TM) Client VM (build 1.5.0_04-b05, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Slackware 10.1.0, SuSE Linux 9.1 (i586)

A DESCRIPTION OF THE PROBLEM :
Combining capturing groups with greedy quantifiers in variety of cases can cause JVM to halt further execution once it reaches Matcher.matches() method.

CPU utilization jumps to 100%, load grows, etc... No exception or JVM error message is being thrown. Solution is to kill the process.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the code. -:) It is the simplest always reproducable case I've found.


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.regex.*;

public class Test {

  public static void main(String[] args) {

    String text = "aaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbb";
    System.out.println(text);

    Pattern p = Pattern.compile("(.*){2,}x");
    Matcher m = p.matcher(text);

    if (m.find()) {
      int start = m.start();
      int end = m.end();

      String matched = text.substring(start, end);
      System.out.println(matched);
    }
  }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
typically possible by not using capturing groups in the same regexp. E.g. \\w{2,} instead of (.*){2,} where applicable.