ArrayIndexOutOfBoundsException in ContentField.activate(...)

We are still using Jahia 4.0.5, but on heavy testing we encounter that the 
workflow process is quite unstable sometimes. When looking in the LOG 
files, I for instance can see an ArrayIndexOutOfBoundsException in the 
ContentField.acivate(...) method.

In this loop we get this exception in the line 
activeAndStagingEntryStates.remove (i);, because i has the value -1. It 
seem strange anyway that the removing from the activeAndStagingEntryStates 
collection is happening in the inner loop and not in the outer loop. As 
you haven't changed the code in the 4.1 version it seems to work for 
everybody else, or could it be that there is a bug?

        // we backup all active entries that will be replaced
        for (int i = 0; i < activeAndStagingEntryStates.size (); i++) {
            ContentObjectEntryState actEntryState = 
(ContentObjectEntryState) activeAndStagingEntryStates.get (
                    i);
            if (actEntryState.isActive ()) {
                for (int j = 0; j < stagedEntries.size (); j++) {
                    ContentObjectEntryState staEntryState = 
(ContentObjectEntryState) stagedEntries.get (
                            j);
                    if (actEntryState.getLanguageCode ().equals (
                            staEntryState.getLanguageCode ())) {
                        // ok appollo, we catched an active entry here! we 
handle this..
                        if (versioningEnabled) {

                            ContentObjectEntryState backupEntryState = 
ContentFieldDB.getInstance ().backupDBValue (
                                    this, actEntryState); // we backup the 
active version
                            // ok we backuped an entry of the field
                            if (backupEntryState != null) {
                                // if the entry state list is loaded, 
let's update it
                                if (versioningEntryStates != null) {
                                    versioningEntryStates.add 
(backupEntryState);
                                }
                                // also we must call the changeEntryState 
because, like, we changed the version or 
                                // something hehe..
                                this.changeEntryState (actEntryState, 
backupEntryState,
                                        jParams, stateModifContext);
                            }
                        } else {
                            // if versioning is not enabled, we delete the 
old value content!
                            this.deleteEntry (actEntryState);
                        }
                        // we then delete the active entry
                        ContentFieldDB.getInstance ().deleteDBValue (this, 
actEntryState);
                        activeAndStagingEntryStates.remove (i);
                        i -= 1;
                    }
                }
            }
       }

Greetings,
Benjamin Papez