Nightracer,
Your other code is failing because you don't have an "End Sub" statement before you're calling another Sub statement. You cannot have a Sub or Function statement inside another Sub or Function statement.
I altered Mike's very nice starting point a bit. This would give you the elapsed time in cell C4. In my test wb, I named had three buttons named, btnResetTimer, btnStartTimer and btnStopTimer.
In a Standard module
<font face=Courier New><SPAN style="color:#00007F">Dim</SPAN> SchedRecalc <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Date</SPAN>, datStartTime <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Date</SPAN>
<SPAN style="color:#00007F">Sub</SPAN> RecalcTimer()
<SPAN style="color:#00007F">Dim</SPAN> wbk <SPAN style="color:#00007F">As</SPAN> Workbook
<SPAN style="color:#00007F">Dim</SPAN> ws <SPAN style="color:#00007F">As</SPAN> Worksheet
<SPAN style="color:#00007F">Set</SPAN> wbk = ThisWorkbook
<SPAN style="color:#00007F">Set</SPAN> ws = wbk.Sheets(1) <SPAN style="color:#007F00">' <== Change the "1" to appropriate #</SPAN>
<SPAN style="color:#007F00">'ws.Range("C3").Value = Format(Now, "dd-mmm-yy")</SPAN>
ws.Range("C4").Value = Format(Now - datStartTime, "hh:mm:ss")
<SPAN style="color:#00007F">Call</SPAN> SetTimer
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#00007F">Sub</SPAN> SetTimer()
<SPAN style="color:#00007F">If</SPAN> datStartTime = 0 <SPAN style="color:#00007F">Then</SPAN> datStartTime = Now
SchedRecalc = Now + TimeValue("00:00:01")
Application.OnTime SchedRecalc, "RecalcTimer"
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#00007F">Sub</SPAN> StopTimer()
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">Resume</SPAN> <SPAN style="color:#00007F">Next</SPAN>
Application.OnTime EarliestTime:=SchedRecalc, _
Procedure:="RecalcTimer", _
Schedule:=<SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#00007F">Sub</SPAN> ResetTimer()
datStartTime = 0
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
</FONT>
In the Worksheet module for the worksheet with the buttons.
<font face=Courier New><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> btnResetTimer_Click()
ResetTimer
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> btnStartTimer_Click()
SetTimer
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
<SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> btnStopTimer_Click()
StopTimer
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
</FONT>
HTH