long product names

Some of my products names have 100+ characters. I tried changing the DB and set "products_description -> products_name" to varchar(255).
As soon as I did that, all of my descriptions were gone. I'm using EasyPopulate, but the import simply doesn't work. It loads without errors but there is still no description. If I go to edit a product, there's no description there, but adding a description manually works fine.

I tested my install over and over again and it all works great until I change the products_name varchar in the DB.

Does anyone have an idea what I'm doing wrong?

Thanks in advance.

Sorry, forgot the specs:
1.3.9d
php 5
mysql 5
EasyPopulate csv 1.2.5.7

I also tested adding a product description manually and it works.
After that, i tested EP again but it doesn't work. However, if I upload only products_image or products_name via EP, it gets changed!