new dog afraid of boyfriend

Question
Hi!
I just rescued a 6-8mo. old Australian Cattle Hound/ Lab mix from the SPCA.  She got along great with me and after I adopted her I took her to my family's holiday picnic where she met other people and their dogs.  She had no problems with anymore, except she was a little more skittish around the younger males until she saw that they meant no harm.  I took her home and was dying for my boyfriend of 4 years to come home from work to meet her.  When he came in the door she started barking and growling at him.  It took almost 1/2 hour to calm her down.  He threw a ball for her and gave her treats and eventually she was fine.  She slept next to our bed and woke us both up in the morning with kisses.  I figured everything was okay and that she just needed to get to know him.  This morning he ran to the store and was gone 5 or so minutes.  When he came back in she began with the same behavior - barking and growling.  I don't want this to happen to him every time he comes home, but I love the dog and am not ready to give up.  We plan on crating her when we're both not home, but I'm afraid of what will happen if he comes home when I'm not here or that the behavior will continue.  Any thoughts?  Thanks so much!
Jill

Answer
I really do all I can to encourage adopting older dogs.  Unfortunately, sometimes they come with past baggage.  What you are doing sound good.  Include walks and obedience training.  If it doesn't help before long, you may need a private trainer or behaviorist.