Java "ConcurrentModificationException" runtime error when iterating .next()

According to the runtime error message the Exception occurs in the following line;

VirusData v = iteratorVirusDB.next();

VirusData is a class with a constructor and an overloaded constructor containing specific information about each of the viruses in the database such as;

• String vName
• String vDefinition

Overloaded with

• Array with Tokenized definition (separated in groups of xLength)
• Array with LCS Tokens
• Float with a grade

iteratorVirusDB of type <VirusData> is an .iterator() of VirusDB, as shown bellow:

Iterator<VirusData> iteratorVirusDB = virusDB.iterator();

VirusDB is and ArrayList of type <VirusData> where I store the virus objects (name and def at this point) so that I can use them later.

ArrayList <VirusData> virusDB = new ArrayList<VirusData>();

And to end with, the error occurs in this method which uses all of the above explained:

private void selectDabataseMouseClicked(java.awt.event.MouseEvent evt) {
    while(iteratorVirusDB.hasNext()) {
        VirusData v = iteratorVirusDB.next();               //ERROR LINE
        String vSig = v.signature;                              
        v.tokens = tokenize.raw(vSig, true, tLength);
        ...
     }
     ...
}

I could really do with some help and advice on how to approach this problem in order to get get the program to run successfully. Bellow, the full StackTrace:

run:
Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
        at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
        at java.util.AbstractList$Itr.next(AbstractList.java:343)
        at project_cle