Dog's reaction when seeing other dogs...

Ok so here's an interesting one for you.

My housemates beagle has seemed to pick up a very strange habit.

When on the lead, and she spots another dog, she immediately stops and either sits or lies down. She is a very friendly dog, never had any issues with her and other dogs. We have both tired encouraging her with voice, treats, toys to continue walking forward...nothing. Then she will either wait for the dog to get to her...or bound over when its gets close enough.

Interestingly. Off lead. If she spots another dog, she is gone...runs straight over to say hi without a second thought. (she is back on the long line, and we are training)

Now...what on earth? Any ideas how I can encourage her to keep walking on even with another dog in sight. The dog could either be walking towards her, or 50 yards on the other side of the field. She just won't move.

Many Thanks in advance.

My dog does this if off lead. Sees a dog in the distance and just drops down with her head between her paws until it reaches her (looks very submissive). She is lively and friendly enough once they reach her.

Better than having her leaping all over every strange dog that approaches us!

Yes, that's exactly what she does on first approach. Her head is down, tail between legs, back a little up. I know she would never attack another dog, she is just being either nervous/shy. Two seconds later she is bounding around them.

Do you feel her stopping before she sees the dog is nervousness maybe..and how could we overcome that?

I walk a golden retriever that does this. She is a very polite dog and has good canine communication skills.

She will not approach a dog head on but will arc and then sniff from behind. Good doggy manners. So, when she is on the lead if I arc when there is an oncoming dog she continues on her way.