Not responding just means it's busy running your queries. It will eventually "recover" but how long that takes will be a function of how complex your queries are. I used to have queries that took 20 minutes or more to retrieve data from tables with several million records so I know of this. Solved that problem by running them at night when no one was there.
If the operation takes too long for you, you'll have to look into why they are slow to complete.
EDIT - it might help to see a pic of your table relationships if you created them.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.