Hi Dave,
It is odd that your sp_help doesn't include an in_row_length value in the columns output.
Perhaps you have an older version of sp_help installed?
Please compare the sp_version output for "installmaster" with your server version from select @@version.
The first 4 bytes of a textpointer should hold the page number of the page containing the first text page of an off-row value. If the text value in an in-row value, the page number would be the page containing the data row, and be followed by the row number of the row containing the value. It looks like AseBulkCopy.WriteToServer() is somehow inserting an invalid value for the text pointer. I don't find any known bugs on it for this issue.
How is the data extracted from SQL Server? If by BCP, is it human-readable ascii or binary native format?
-bret