A family of Microsoft relational database management systems designed for ease of use.
So that's 238 columns? A Table is limited to 256 columns so you're not quite to the limit, but it's quite possible that the wizard has some overhead. Another limit is that any single row is limited to 2000 characters, so if a lot of these fields are Text you may be exceeding that limit.
If that's not the case, try creating a new, empty table (perhaps by importing, design view only); linking to the spreadsheet; and Appending to the table. Or you may need to import the spreadsheet piecemeal into more than one table.
In any case I'd hope you'll be normalizing this into a proper relational database - 50 columns is enormously wide, and 238 is just plain wrong.