This is actually a UDF (user-defined function) that will return a count of the comments that contain your string, and make the comments visible.
<font face=Courier New><SPAN style="color:#00007F">Function</SPAN> CountCmt(<SPAN style="color:#00007F">ByRef</SPAN> Range <SPAN style="color:#00007F">As</SPAN> Range, <SPAN style="color:#00007F">ByRef</SPAN> FindWhat <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN>, <SPAN style="color:#00007F">Optional</SPAN> <SPAN style="color:#00007F">ByRef</SPAN> CaseSensitive <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Boolean</SPAN>) <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Double</SPAN>
Application.Volatile
<SPAN style="color:#00007F">Dim</SPAN> c <SPAN style="color:#00007F">As</SPAN> Range
<SPAN style="color:#00007F">Dim</SPAN> s <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> e <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> g <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> l <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> d <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Double</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> t <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN>
<SPAN style="color:#00007F">Dim</SPAN> f <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">String</SPAN>
d = 0
g = Len(FindWhat)
f = FindWhat
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">Resume</SPAN> <SPAN style="color:#00007F">Next</SPAN>
<SPAN style="color:#00007F">For</SPAN> <SPAN style="color:#00007F">Each</SPAN> c <SPAN style="color:#00007F">In</SPAN> Range.Cells
s = 1
e = Len(c.Comment.Text)
t = c.Comment.Text
<SPAN style="color:#00007F">Do</SPAN> <SPAN style="color:#00007F">While</SPAN> s <= (e - g)
<SPAN style="color:#00007F">If</SPAN> s = 0 <SPAN style="color:#00007F">Then</SPAN> <SPAN style="color:#00007F">Exit</SPAN> <SPAN style="color:#00007F">Do</SPAN>
<SPAN style="color:#00007F">If</SPAN> CaseSensitive <SPAN style="color:#00007F">Then</SPAN>
s = InStr(s, t, f, vbBinaryCompare)
<SPAN style="color:#00007F">Else</SPAN>
s = InStr(s, t, f, vbTextCompare)
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN>
<SPAN style="color:#00007F">If</SPAN> s > 0 <SPAN style="color:#00007F">Then</SPAN> c.Comment.Visible = True: d = d + 1: s = s + g <SPAN style="color:#00007F">Else</SPAN> c.Comment.Visible = <SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#00007F">Loop</SPAN>
e = 0
<SPAN style="color:#00007F">Next</SPAN>
<SPAN style="color:#00007F">On</SPAN> <SPAN style="color:#00007F">Error</SPAN> <SPAN style="color:#00007F">GoTo</SPAN> 0
CountCmt = d
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Function</SPAN></FONT>