I am using
Eclipse: 20100218-1602 (3.5 with latest online updates)
Scala-Plugin: 1.0.0.201009250004

While working on a ZK-Projekt where I had added "scala nature" I got the following AssertionError:

at pos RangePosition(PersonPanel.scala, 365, 365, 365) was found: java{java.type}.util{java.util.type}[356:365]
already attributed
typeMembers at java{java.type}.util{java.util.type} java.util.type
ScalaPlugin--TRACE--2655131--main--:No completions
java.lang.AssertionError: assertion failed: class EnumMap: package util
at scala.tools.nsc.symtab.classfile.ClassfileParser.parseMethod(ClassfileParser.scala:603)
at scala.tools.nsc.symtab.classfile.ClassfileParser$$anonfun$1$$anonfun$apply$mcV$sp$2.apply$mcVI$sp(ClassfileParser.scala:525)
at scala.collection.immutable.Range$ByOne$class.foreach$mVc$sp(Range.scala:285)
at scala.collection.immutable.Range$$anon$2.foreach$mVc$sp(Range.scala:265)
at scala.tools.nsc.symtab.classfile.ClassfileParser$$anonfun$1.apply$mcV$sp(ClassfileParser.scala:525)
at scala.tools.nsc.symtab.classfile.ClassfileParser.parseClass(ClassfileParser.scala:542)
at scala.tools.nsc.symtab.classfile.ClassfileParser.parse(ClassfileParser.scala:98)
at scala.tools.nsc.symtab.SymbolLoaders$ClassfileLoader.doComplete(SymbolLoaders.scala:247)
at scala.tools.nsc.symtab.SymbolLoaders$SymbolLoader.complete(SymbolLoaders.scala:61)
at scala.tools.nsc.symtab.SymbolLoaders$SymbolLoader.complete(SymbolLoaders.scala:35)
at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:743)
at scala.tools.nsc.symtab.Symbols$Symbol.tpe(Symbols.scala:718)
at scala.tools.nsc.symtab.Symbols$Symbol.tpeHK(Symbols.scala:903)
at scala.tools.nsc.symtab.Types$Type.computeMemberType(Types.scala:527)
at scala.tools.nsc.symtab.Types$Type.memberType(Types.scala:524)
at scala.tools.nsc.interactive.Global.addTypeMember$1(Global.scala:423)
at scala.tools.nsc.interactive.Global$$anonfun$typeMembers$1.apply(Global.scala:445)
at scala.tools.nsc.interactive.Global$$anonfun$typeMembers$1.apply(Global.scala:444)
at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:61)
at scala.collection.immutable.List.foreach(List.scala:45)
at scala.tools.nsc.symtab.Scopes$Scope.foreach(Scopes.scala:310)
at scala.tools.nsc.interactive.Global.typeMembers(Global.scala:444)
at scala.tools.nsc.interactive.Global$$anonfun$getTypeCompletion$1.apply(Global.scala:396)
at scala.tools.nsc.interactive.Global$$anonfun$getTypeCompletion$1.apply(Global.scala:396)
at scala.tools.nsc.interactive.Global.respond(Global.scala:276)
at scala.tools.nsc.interactive.Global.getTypeCompletion(Global.scala:396)
at scala.tools.nsc.interactive.CompilerControl$$anon$4.apply$mcV$sp(CompilerControl.scala:105)
at scala.tools.nsc.interactive.Global.pollForWork(Global.scala:132)
at scala.tools.nsc.interactive.Global$$anon$2.run(Global.scala:192)