I tried using Chip's Win API code at...

(Using Windows Timers)
http://www.cpearson.com/excel/ontime.htm

It ran fine, except when I was in the Edit mode. Without fail, it
shuts down Excel with no dialog box or other warning. On restart, it
shows the file as been recovered from a crash.

?? What am I doing wrong? Is there a library to reference? I couldn't
find one.

Windows 2000 5.002195 SP3
Excel 2002 SP1

TIA, and here's the code:

Public Declare Function SetTimer Lib "user32" ( _
ByVal HWnd As Long, ByVal nIDEvent As Long, _
ByVal uElapse As Long, ByVal lpTimerFunc As Long) As Long
Public Declare Function KillTimer Lib "user32" ( _
ByVal HWnd As Long, ByVal nIDEvent As Long) As Long

Public TimerID As Long
Public TimerSeconds As Single

Sub StartTimer()
TimerSeconds = 5 ' how often to "pop" the timer.
TimerID = SetTimer(0&, 0&, TimerSeconds * 1000&, AddressOf
TimerProc)
End Sub

Sub EndTimer()
On Error Resume Next
KillTimer 0&, TimerID
End Sub

Sub TimerProc(ByVal HWnd As Long, ByVal uMsg As Long, _
ByVal nIDEvent As Long, ByVal dwTimer As Long)
'
' The procedure is called by Windows. Put your
' timer-related code here.
'
Range("a1").Value = Now()
End Sub