XL 2004 macro crashes while looping through workbooks

> I have a series of macros which cycle through identically structured
> workbooks, collecting and reporting information from each. The macros
> work(ed) fine in xl2001 and xl.x, but not in 2004. At first I found
> that findfile had been dropped but replaced it using Dir. This works in
> all 3 versions of xl but only briefly in xl2004. After a few (3-10)
> cycles of looping, xl2004 will crash. I've only been able to avoid this
> by disabling the statement which closes the sampled workbook at the
> conclusion of the loop. No real solution since some of the macros cycle
> through >1000 workbooks. Here's one of the problem chidren:
>
> Dim stufile, cursht, studentsPath
> SetPaths ' Set the path to top level of folders
> stufile = Dir(MainPath & stufolder(J) & aps & "open" & aps, vbNormal)
> 'names first file in stufolder (J) aps = '
>
> path separator
> cursht = ActiveSheet.Name
> Do While stufile <> "" ' Start the loop.
> If LCase(Left(stufile, 3)) = _
> stufolder(J) And (Right(stufile, 1) = "H" Or Right(stufile,
> 1) = "C" Or Right(stufile, 4) = "H.xls" Or Right(stufile, 4) = "C.xls")
> Then ' trap for stray files
> DisableEventsAlerts
> Workbooks.Open studentsPath & stufolder(J) & aps & "open" & aps
> & stufile
> EnableEventsAlerts
> monthlywrkshtdata 'read stats from each open workbook
> DisableEventsAlerts
> ActiveWorkbook.Saved = True
> ActiveWorkbook.Close
> EnableEventsAlerts
> Else 'note any non-midas files found on error log
> ...
> End If
> stufile = Dir 'get next file
> Loop
> 'Next
> End Sub
>
> Why does xl2004 crash while looping and why would closing workbooks be
> a factor (there are no on-close events)? I've updated, repaired
> permissions, dumped prefs, etc. I have a G5 imac and 10.4.8. I hope
> this makes sense. Any help appreciated.