Need other opinoins on my problem.?

i have a friend at work thats a guy and he just got back. he got moved into a diffrent department. and now this other girl has been talking to him a lot. and i found that they are friends. so im like thats cool. i went over their a few times. one night she saw that i was their and my friend didnt know because he didnt see me. my area is right next to theirs so if i wanted to i could go up and say hi. well she went down on break and i went over and i said hi to him. and he was shocked to see me. after that i noticed he started staring at me and it started to make me laugh because he was being silly. after work i wanted to talk to him. but he was takeing his time. i saw her and she hung out in her car for awhile. i closed my door and then i saw him and im like oh never mind its late and i got to get home so i just honked my horn and waved at him, and then i left 2 minuts after i turned the corner she was on my tail. and i saw him trying to get her to stop. i was going 45 on a 15 zone because she was on my and i was trying to get over. well he finally got her to stop and i saw them pull over somewhere. i didnt stay because my parents time me from when i call to make sure im ok i guess. well now my friend is back in his regular department and shes moved near mine and every time i see her i try to be nice and she just scowls at me. and or trys to avoid me. which thats fine because im doing the same. its just we keep bumbing into each other. but now my friend is being weird and hes trying to avoid haveing a full convosation with me. on friday and i was closeing with him. so i was like forget it. and just half hr after closeing time i went over to check the time and just put my hands on my head and was spaceing. havent been feel that great. and then i moved slightly and i saw that my friend was stareing at me. iv noticed hes been trying to get my attention friday but when i went to go see him he tried to stay away. i dont understand him. and i dont know what that girls prob is. can someone give me a little advice please!