Dominance to smaller / more submissive dogs?

We've been having an issue with this for about 6 months now...Laika is 17 months and the most submissive dog in the world to people, bigger dogs or dogs that are even remotely dominant (my parent's Lhasa Apso takes NO nonsense from her!)

The problem lies with puppies, smaller dogs or more submissive ones.  If the dog lies on it's back or squeals she goes rigid, pins it down by lying on top of it and growls really loudly into its face!  It's horrible and sounds like she's going to kill it! However we've noticed when she's done this she has NEVER bitten the other dog, just showed teeth and made loads of horrible noises.

With a dog that shows even the slightest dominant tendencies she'll be the softest thing around.

It so embarrassing as I'm a dog groomer and she meets so many dogs every day.  I worry the owners are going to get the wrong idea about her with the whole "staffy reputation"

Anyone else experienced this?  Any suggestions on dealing with it?

I haven't I'm afraid, daisy is not interested in small dogs at all! Sure somebody will have come across this though x

Bacchus has shown exactly the same behaviour since he was a small pup. Only difference is he is not submissive towards any other dog. The opposite is the case with him. If any other dog tries to show dominance he will retaliate. He's fine with the dogs he grew up with but is dog aggressive with unfamiliar dogs so I have to be very careful about where and when I give him off-lead exercise.