Without going into a lot of detail, I understand what you are going through and how you probably feel right now.  Many on this board do and many on this board will think of you as a melodramatic whiner.  Such is life.

To answer some of your questions, let me first start by saying that I only have experience with the Special Agent process but I believe policies regarding the FBI polygraph would be the same for SA and support positions.

With that in mind, I can tell you that the FBI does allow polygraph retests AT THEIR DISCRETION under certain circumstances.  Primarly, you are ineligble for a retest if you a)disclosed any information to the examiner AFTER your data gathering session (i.e. hooked to the machine) that had not already been disclosed and/or b)were found deceptive on relevant questions relating to national security issues.

If neither condition applies to you, a retest might be possible.  Call your applicant coordinator until you get him/her on the phone.  Indicate that you are disputing the results and you will be sending a letter to him/her.  In the letter, address the following items:  your examiner's name, examination date, position applied for, your background (summary of what you can bring to the FBI), problems on polygraph as mentioned by the examiner, any reasons you feel those problems existed (e.g. something on your mind, etc.), the fact that you did NOT disclose any previously undisclosed information and the fact that you want a retest.  Address the letter to the Applicant Coordinator and get it off as soon as possible.  Call to make sure he/she got it.  Call every two weeks or so to see where things stand.  The letter will be sent to HQ for a determination, you will then be interviewed by an agent to determine "sincerity" and best case scenario will face another polygraph.

It sounds like you may have been accused of deception relating to national security based on your description.  I can't say for sure that a retest is not possible but from what I understand, it may not be.  However, check and make sure that this was actually a question you indicated deception on; I have seen the polygrapher's statements on problems and the ACTUAL problem vary somewhat.

Hopefully your clarification of drug use did take place before your examination and you indicated after data gathering exactly (and only) what you indicated before data gathering.

Finally, as far as I know a polygraph failure will prevent you from reapplying for the FBI in the future and will not allow your other FBI position applications to be processed further.  I am truly sorry and I wish you the best.