Whenever I try and import one of two QIF files saved from Quicken (which
version, unfortunately, I'm not sure), gnucash crashes.  Before crashing it
does get through the import stuff to the point where it's checking for
duplicate transactions and then the bar gets to maybe 1/3 of the way across
before crashing.  The QIF file in question contains a lot of buy and sell
information for a stock account.

The backtrace reads:
In unknown file:
   ?:  0* [gnc:group-find-duplicates # #]
In /usr/share/gnucash/scm/qif-import/qif-merge-groups.scm:
  38:  1* (let* (# # # # ...) (if # #) (for-each # new-xtns) ...)
  55:  2* [for-each #<procedure #f (xtn)> (# # # # ...)]
In unknown file:
   ?:  3  (if (null? rest) (letrec ((lp #)) (lp list1)) ...)
    ...
   ?:  4  (begin (f (car l)) (lp (cdr l)))
   ?:  5* [#<procedure #f (xtn)> #<gw:wcp <gnc:Transaction*> 0x8d2fef8>]
In /usr/share/gnucash/scm/qif-import/qif-merge-groups.scm:
  57:  6  (let ((query (gnc:malloc-query))) (set! work-done (+ 1
work-done)) ...)
  73:  7* (let ((date #)) (gnc:query-add-date-match-timepair query #t ...))
  74:  8  [gnc:query-add-date-match-timepair #<gw:wcp <gnc:Query*>
0x8875f90> #t ...
  75:  9*  [decdate (-1 . 0) #(0 0 0 7 0 0 0 0 -1 ...)]
In /usr/share/gnucash/scm/date-utilities.scm:
 151: 10   [moddate #<procedure #f (d1 . ds)> (-1 . 0) #(0 0 0 7 0 0 0 0 -1
...)]
     ...
  36: 11   [gnc:secs->timepair ...
  36: 12*   [car ...
  36: 13*    [mktime #(59 59 18 24 11 69 3 364 -1 ...)]

/usr/share/gnucash/scm/date-utilities.scm:36:28: In procedure mktime in
expression (mktime date):
/usr/share/gnucash/scm/date-utilities.scm:36:28: Success