run-time error '-2147417848 (80010108)

I have an excel macro that runs every half hour and now produces the following error:
run-time error '-2147417848 (80010108)
Automation error
The object invoked has disconnected from its clients.

I can temporarily fix it by creating a new spreadsheet with all the formatting and then importing the macro. However it will start to fail after several days of running.
The basic flow of the macro is
1). select first sheet
2). load text file
3). format the data
4). load next sheet
.
.
.

I have six sheets in the workbook and six text files to work on, one file per sheet.
this is the line that fails from the format sub routine:
Selection.Delete Shift:=xlUp

I have copied the macro into a text file and attached it to this post.