I was importing, deploying and deleting various versions of the javaee-web app when I on a new app creation/import got ~20 of these in the log:

eclipse.buildId=unknown
java.version=1.6.0_31
java.vendor=Apple Inc.
BootLoader constants: OS=macosx, ARCH=x86, WS=cocoa, NL=en_US
Framework arguments: -product com.jboss.jbds.product.product -keyring /Users/max/.eclipse_keyring -showlocation
Command-line arguments: -os macosx -ws cocoa -arch x86 -product com.jboss.jbds.product.product -keyring /Users/max/.eclipse_keyring -consoleLog -showlocation

Error
Fri Jun 22 15:34:09 CEST 2012
second does not exist

Java Model Exception: Java Model Status [second does not exist]
at org.eclipse.jdt.internal.core.JavaElement.newJavaModelException(JavaElement.java:505)
at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:246)
at org.eclipse.jdt.internal.core.JavaElement.openWhenClosed(JavaElement.java:518)
at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:255)
at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:241)
at org.eclipse.jdt.internal.core.JavaProject.getJavaProjectElementInfo(JavaProject.java:1638)
at org.eclipse.jdt.internal.core.JavaProject.newNameLookup(JavaProject.java:2325)
at org.eclipse.jdt.internal.core.JavaProject.newNameLookup(JavaProject.java:2335)
at org.eclipse.jdt.internal.core.JavaProject.findType(JavaProject.java:1354)
at org.eclipse.jdt.internal.core.JavaProject.findType(JavaProject.java:1261)
at org.jboss.tools.common.util.EclipseJavaUtil.findType(EclipseJavaUtil.java:78)
at org.jboss.tools.common.java.ParametedTypeFactory.getParametedType(ParametedTypeFactory.java:127)
at org.jboss.tools.common.java.ParametedTypeFactory.getParametedType(ParametedTypeFactory.java:79)
at org.jboss.tools.cdi.internal.core.impl.definition.ParameterDefinition.init(ParameterDefinition.java:47)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.setAnnotatable(AbstractMemberDefinition.java:65)
at org.jboss.tools.cdi.internal.core.impl.definition.ParameterDefinition.setLocalVariable(ParameterDefinition.java:41)
at org.jboss.tools.cdi.internal.core.impl.definition.MethodDefinition.loadParamDefinitions(MethodDefinition.java:87)
at org.jboss.tools.cdi.internal.core.impl.definition.MethodDefinition.init(MethodDefinition.java:63)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.setAnnotatable(AbstractMemberDefinition.java:65)
at org.jboss.tools.cdi.internal.core.impl.definition.MethodDefinition.setMethod(MethodDefinition.java:48)
at org.jboss.tools.cdi.internal.core.impl.definition.TypeDefinition.init(TypeDefinition.java:70)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractMemberDefinition.setAnnotatable(AbstractMemberDefinition.java:65)
at org.jboss.tools.cdi.internal.core.impl.definition.AbstractTypeDefinition.setType(AbstractTypeDefinition.java:72)
at org.jboss.tools.cdi.internal.core.impl.CDIProject.rebuildBeans(CDIProject.java:1263)
at org.jboss.tools.cdi.internal.core.impl.CDIProject.update(CDIProject.java:1118)
at org.jboss.tools.cdi.internal.core.impl.definition.DefinitionContext.applyWorkingCopy(DefinitionContext.java:390)
at org.jboss.tools.cdi.core.CDICoreBuilder.build(CDICoreBuilder.java:230)
at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:728)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:199)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:239)
at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:292)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:295)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:351)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:374)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:143)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:241)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)

"second' is the name of the project that yes, does not exist since it was deleted.