Are there any errors in Eclipse log?
in help/about eclipse/configuration details/view error log, i have a log of 700ko with a lot of:
!ENTRY org.eclipse.wst.validation 4 0 2009-02-25 15:20:25.299 !MESSAGE Marker id 78304 not found. !STACK 1 org.eclipse.core.internal.resources.ResourceException: Marker id 78304 not found. at org.eclipse.core.internal.resources.Marker.checkInfo(Marker.java:56) at org.eclipse.core.internal.resources.Marker.getAttribute(Marker.java:97) at org.eclipse.wst.validation.internal.TaskListUtility.getValidationTasks(TaskListUtility.java:245) at org.eclipse.wst.validation.internal.TaskListUtility.getValidationTasks(TaskListUtility.java:286) at org.eclipse.wst.validation.internal.TaskListUtility.getValidationTasks(TaskListUtility.java:333) at org.eclipse.wst.validation.internal.TaskListUtility.removeTaskSubset(TaskListUtility.java:426) at org.eclipse.wst.validation.internal.TaskListUtility.removeAllTasks(TaskListUtility.java:406) at org.eclipse.wst.validation.internal.TaskListUtility.removeAllTasks(TaskListUtility.java:402) at org.eclipse.wst.validation.internal.TaskListUtility.removeAllTasks(TaskListUtility.java:390) at org.eclipse.wst.validation.internal.operations.WorkbenchReporter.removeAllMessages(WorkbenchReporter.java:129) at org.eclipse.wst.validation.internal.operations.ValidationOperation.removeOldMessages(ValidationOperation.java:1048) at org.eclipse.wst.validation.internal.operations.ValidationOperation.launchJobs(ValidationOperation.java:1305) at org.eclipse.wst.validation.internal.operations.ValidationOperation.validate(ValidationOperation.java:795) at org.eclipse.wst.validation.internal.operations.ValidationOperation.run(ValidationOperation.java:614) at org.eclipse.wst.validation.internal.operations.ValidationBuilder.build(ValidationBuilder.java:170) at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:633) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:170) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:201) at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:253) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37) at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:256) at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:309) at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:341) at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:140) at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:238) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) !SUBENTRY 1 org.eclipse.core.resources 4 376 2009-02-25 15:20:25.299 !MESSAGE Marker id 78304 not found.