Britney Spears' Ex Under Felony Investigation

We've learned Adnan Ghalib -- the one-time boyfriend of Britney Spears who is under court order to stay away from her -- is under investigation for felony assault with a deadly weapon with a vehicle.

Here's what went down. Yesterday morning, a process server went to Ghalib's Encino apartment to hand him legal papers ordering him to appear in the restraining order case.

The process server was waiting for Adnan Ghalib in the alley when Ghalib rolled up and allegedly hit the dude with his car. The process server says he landed on the hood of Adnan's car.

Adnan allegedly fled the scene and the process server called cops at 10:42 AM. Police arrived and noticed the process server had cuts and scratches, but he refused treatment.

The case is under investigation. Ghalib is the suspect and the alleged crime is assault with a deadly weapon with a vehicle -- a felony.

We spoke with Ghalib -- he had no comment.