These problems have included:

a) Origin telling me that a perfectly legitimate file was not legal ASCII

b) Origin deleting the first one or two characters of the first field of the
first data row of a file (the second line, after the headers).

BUG FOUND: although Origin in most situations tolerates normal UNIX
files whose lines end with a newline (NL, LF, ^J) only, it seems that the code
that reads in the column names requires a carriage return (CR, ^M) at the
end of the line. When I added a carriage return to the end of the line, making
it CR LF, the above problems went away.

This was deceiving, because newline only files work fine in all other cases
that I have tried.

Test cases: I attach these to mail I have sent to Origin.

The Origin ASCII Import routines are powerful and flexible and compare favorably to many other software packages. While any ASCII file is "legitimate", our "intelligent" import routine sometimes needs some extra help from the user. (I too hesitate to call any software "intelligent" and certainly don't expect it will ever be psychic.)
For the example ASCII file you provided, I opened the File:Import:ASCII Options dialog and set the following options:

Delimited CHECK
Delimiter Tab
Automatic determination of column types UNCHECKED
Skip main header, number of lines 1
Specify known subheader lines CHECKED (number = 0)
# of Columns CHECKED (value = 6)

Origin imports the data completely without modifying the original data file. Once the data has been imported, you can save the worksheet as a template (select File:Save Template As.. from the main menu and save the template with an appropriate name). Any time you need to import data in this file format, choose File:New from the menu, select Worksheet for the Window Type and select the template. You can just select File:Import:ASCII from the menu since the template remembers the appropriate settings.