Error in "nameModule header{v a1Ax}"

'''1. Linux version:''' 2.4.27
'''2. GCC version:''' 3.3.5 (Debian 1:3.3.5-13)
'''3-4. Sequence of events:'''
zdiles@victor:~/lab/NetGremlins/newSiteManager$ ghci -v eventsCons.hs
   ___         ___ _
  / _ \ /\  /\/ __(_)
 / /_\// /_/ / /  | |      GHC Interactive, version 6.6.1, for Haskell 98.
/ /_\\/ __  / /___| |      http://www.haskell.org/ghc/
\____/\/ /_/\____/|_|      Type :? for help.

Using package config file: /usr/local/lib/ghc-6.6.1/package.conf
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
Hsc static flags: -static
Loading package base ... linking ... done.
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
*** Chasing dependencies:
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
Upsweep completely successful.
*** Deleting temp files:
Deleting:
*** Chasing dependencies:
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
compile: input file eventsCons.hs
*** Checking old interface for main:EventsCons:
[1 of 1] Compiling EventsCons       ( eventsCons.hs, interpreted )
*** Parser:
*** Renamer/typechecker:
*** Desugar:
    Result size = 487
*** Simplify:
    Result size = 2468
    Result size = 1293
    Result size = 1291
    Result size = 1291
*** Tidy Core:
    Result size = 1291
*** CorePrep:
    Result size = 1475
*** ByteCodeGen:
*** Deleting temp files:
Deleting:
Upsweep completely successful.
*** Deleting temp files:
Deleting:
Ok, modules loaded: EventsCons.
*EventsCons> main
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
Loading package haskell98 ... linking ... done.
Loading package parsec-2.0 ... linking ... done.
Loading package network-2.0.1 ... linking ... done.
Loading package HTTP-3000.0.0 ... linking ... done.
Loading package HUnit-1.1.1 ... linking ... done.
Loading package hxt-7.2 ... linking ... done.
ghc-6.6.1: panic! (the 'impossible' happened)
  (GHC version 6.6.1 for i386-unknown-linux):
        nameModule header{v a1Ax}

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

*EventsCons>

'''5. As can be seen in the listing it gives the error:'''
ghc-6.6.1: panic! (the 'impossible' happened)
  (GHC version 6.6.1 for i386-unknown-linux):
        nameModule header{v a1Ax}

'''6. Source code:'''
  1 module EventsCons where
  2 import Text.XML.HXT.Arrow
  3 import Data.Tree.NTree.TypeDefs (NTree (..))
  4 import System.Time
  5 import List
  6
  7 myMonths = [January .. December]
  8 monthRefs = zip [January .. December]
  9                 ["#jan", "#feb", "#mar", "#apr", "#may", "#jun",
 10                   "#jul", "#aug", "#sep", "#oct", "#nov", "#dec"]
 11
 12
 13 main =
 14   runX ( readDocument [(a_validate, v_0)] "events.xml" >>>
 15           processEvents myMonths >>>
 16           writeDocument [(a_indent, v_1)] "events.html" )
 17
 18
 19 processEvents months =
 20   processTopDown (monthListX months)
 21
 22
 23 monthListX months =
 24   mkelem "div" [sattr "class" "monthlist"]
 25     ([header] ++
 26       (listMonths $ take 6 months) ++
 27       [breakTag] ++
 28       (listMonths $ drop 6 months) ++
 29       [breakTag, archive, breakTag])
 30     `when`
 31       (isElem >>> hasName "monthList")
 32   where
 33     header = selem "h2" [[txt "Event Galleries"]]
 34     breakTag = selem "br" []
 35     archive = mkelem "a" [sattr "class" "month", sattr "href" "archive.html"]
 36                           [txt "Archive of Previous Years"]
 37     monthLink month = mkelem "a" [sattr "class" "month",
 38                                   sattr "href" (getRef $ lookup month monthRefs)]
 39                                  [txt $ show month]
 40     listMonths = map monthLink
 41 {-
 42 eventListX months events =
 43
 44     `when`
 45     (isElem >>> hasName "eventList")
 46   where
 47     monthGroup month =
 48       mkelem "div" [sattr "class" "month"]
 49         ([mkelem "a" [sattr "name" "jan"]
 50           [mkelem "span" [sattr "class" "month"]
 51             [txt (show month)]],
 52         selem "br" []] ++
 53         concatMap mkEventLink (filter (inMonth month) events) ++
 54         [selem "br" []]
 55     mkEventLink event =
 56       [mkelem "a" [sattr "class" "event", sattr "href" "eventLoc"]
 57                 [txt (eventName event)],
 58       selem "br" []]
 59
 60 -}
 61 -- Tools --
 62
 63 --Turns a lookup reference from "Maybe" to a String
 64 getRef Nothing = ""
 65 getRef (Just val) = val
 66