The following error message occurs when I try to import a tab delimited file containing my new prospects:

What is wrong?
Edit the file you are trying to import using Wordpad, and take out all of the double quotes.
99.9% of all Standard Import problems are because the file intended for import has problems. Following are a couple of suggestions when generating files for import:
Most of the time when you look at a file in Excel, you will not see the double quotes, Excel filters them out (yet they remain in the file). You will see them in Wordpad. The same goes for CSV files, you have to rename a CSV to a TXT then look at the file in Wordpad to see if there are any delimiters in addition to what is known or defined.
Another typical example are comma delimited files that contain commas in the fields, it won’t import properly, and probably won’t allow you to map the fields properly.
A general rule is you cannot have a file for import that contains any standard delimiters (double quotes, single quotes, commas, vertical bars, etc) other than the defined field delimiter.