XL Odd behavior interaction between dynamic range and Sheet_Deactivate macro

I keep a daily log of activities in and Excel Workbook. Each activity
work*** is one week and is named for Monday's date, as in "Dec 23".
In col A I enter the date in 26-Dec format. In Col B I put the
activity. Col C does a vertical lookup based on Col B and a table in
another worksheet called "Sheet2".

Sheet2 contains only a single dynamic range called "Namelist" and the
name is defined as
=OFFSET(Sheet2!$A$1,0,0,COUNTA(Sheet2!$A:$A),2)
It contains a list of the regular activities I do. The VLOOKUP takes
the activity description and looks up who I do that for and places
their name in Col C.

The "Sheet2" activity list changes from time to time. When I pick up a
new regular activity, I add it to the "Sheet2" list so the VLOOKUP can
put in the correct name on the weekly ***. Sometimes when I no
longer do an activity, I delete it from the "Sheet2" list. This is
where the problem is occuring now.

There is also a sheet macro associated with "Sheet2". It automatically
resorts the activity list on Col A, the list of activities, when I
deactivate the ***. This way, I don't have to resort the list after
I add or delete activities, the macro does it for me. But I'm getting
some very strange behavior since I added the macro. Here is the macro:

Private Sub worksheet_deactivate()
'Creates dynamic range in work*** module in DGBStatus workbook
'and sorts dynamic range on Col A for vlookup in other sheets
Dim rNamelist As Range

ActiveWorkbook.Names.Add Name:="namelist", RefersToR1C1:= _
"=OFFSET(Sheet2!R1C1,0,0,COUNTA(Sheet2!C1),2)"
Set rNamelist = Sheet15.Range("namelist")

rNamelist.Sort Key1:=Range("A3"), Order1:=xlAscending,
Header:=xlGuess, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom
End Sub

(Sheet15 is the absolute for "Sheet2")

When I first added the macro, it didn't have the first line inserting
the dynamic range formula into the spread***, and when I deleted
lines from the range, the macro would hang and I'd get a range
variable not working message. I found that the formula for the
"Namelist" range was getting screwed up somehow when I deleted some
lines from the range and it returned a "method range of object
work*** failed" error on the "Set rNamelist..." line. So I added the
line to insert the correct formula everytime the macro runs. Seemed
like a good idea at the time.

But now, when I add or delete line(s) from the "Namelist" range, the
macro runs but when I click on the activity work***. I get very
weird results. If I click on the next blank cell in Col B, the cursor
appears in that cell, but there's no border to indicate I've selected
it. When I click on any other cell in the sprea***, that cell and
the previously selected cell both are higlighted, almost as though I
control clicked on the secone one, except that the originally selected
cell is NOT in reverse, like a previously selected cell in a Control
click sequence normally would be. As I click on different cells at
random in the activity ***, the currently selected cell and the
originally selected call remain with the heavy borders around both of
them!

This behavior continues until I activate another application or close
and reopen the spread***, at which point it stops until I add or
delete another line from the "Sheet2" activity list.

Is this a known bug? A strange interaction between a dynamic range and
an event driven macro? Any ideas or suggestions?
.