|I like your style, Derby!|
1 - I found a number of XLSTART folders.
The one I put the personal.xls file in is "C:\Program Files\Microsoft Office\OFFICE11\XLSTART".
Another folder that stands out is "C:\Documents and Settings\username\Application Data\Microsoft\Excel\XLSTART". I copied the personal.xls file to this folder but personal.xls still didn't open with an existing file.
Other XLSTART folders belong to other users on my computer. All were under "C:\Documents and Settings\...".
2 - I'd already tried the toolbar... I created the Smiley Face button on a new toolbar and assigned to it the macro in the personal.xls file. The Smiley Face appears when I open Excel from the Start menu, however doesn't appear when I open an existing file.
3 (other post) - I checked the file associations and actions associated with opening the file; they match your settings including the "/e" at the end (except my folder is ...\OFFICE11\... where yours is ...\Office10\... .
DDE box is checked and DDE message is identical.
AutoRecover Save Location
Probably irrelevent, but I changed my AutoRecover save location from the default (to a folder in C:\).
I've tested the personal.xls file on a collegues computer and it opened with an existing file.
Excel should be set up in the same way on both our computers. This means my issue is likely caused by something I've changed in Excel's settings.
I just have to identify what it was...