Awhile back I was doing some intense study on spiritual warfare. Read book after book, by authors with different backgrounds. Five books in a row, identified "tongues speaking" as a vehicle used by the Evil Ones to gain access to vulnerable persons, to harass or even "possess". I have a friend with a Pentecostal history, who had continued to do the tongues speaking when she was in "deep prayer", long after she left that congregation. I showed her the material I had found, and she immediately renounced the practice. She has found freedom from much of the feelings of panic and discouragement that had plagued her.
The best book I've found on the subject of tongues speaking, by an author with an SDA background is "Tongues - Dissecting the Gift" by Teresita Perez. It's just a small book, but covers the subject pretty well. She doesn't really go into the spiritual warfare aspect. I have the book posted on my "Recommended Resources" page.
Rachel Cory
Prophecy Viewpoint