How big are your text files: how many characters wide, how many rows
deep or bytes wide? There's a limit on the width; I think it's about
2000 characters total.
I'd start the troubleshooting by checking out the text files.
1) if you split the file into two or more parts, can any of the parts be
imported? If part can and the rest can't, there may be an irregularity
in the file (e.g. a linebreak within a field).
2) make sure that every line in the input file(s) ends with CR+LF
(Chr(13) & Chr(10)). Current versions of Access seem to insist on this.
3) check for and remove blank lines, formfeeds and other things that
shouldn't be in a fixed length file.
4) double-check your import specification. If the file has many fields,
it can be better to use a schema.ini file with the specification: these
are easier to build and edit than specifications in the Import Wizard.
See
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odbc/htm/odbcjetsdk_98.asp
for documentation.
