Running Eclipse with Java 1.6.0 update 21? Please follow the instructions here to resolve crashing and freezing issues.

Oracle/Sun VM 1.6.0_21 on Windows

The Eclipse 3.3 - 3.6 launchers for Windows have a problem with the Oracle/Sun Java VM version '1.6.0_21'. You have three choices to work around this:

1. switch back to '1.6.0_20' (as of July 19, 2010 it can still be downloaded here)
2. Change the commandline for launching or add the following line after "-vmargs" to your eclipse.ini file:
   -XX:MaxPermSize=256m
   (Detailed instructions/examples)
3. For Helios, download the fixed eclipse_1308.dll and place it into
   (eclipse_home)/plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.0.v20100503

The bug itself is open for voting and comments as 6969236 on the Java BugParade, and as bug 319514 on the Eclipse side.