Excel REFUSES to open a file in the startup directory....

I have a file (operations.xls) in the startup directory.
This file has opened successfully for over 2 years now.
This morning I got a VB400 err msg.
NOW Excel refuses to open this file.
If I double click the file excel will open it.
If I re-name it and restart Excel, it will open from the startup directory.
I am totally dumb founded - never had an issue like this.
ANY help MUCHLY appreciated.

when Excel gave the vb400 err msg it disabled the file.

> Excel Options > Addins > (Manage) (Select Disabled Items) > GO > selected operations.xls > Enable > Close