This may be because you are deleting so many files at one time. Could you try to lower the number and see if it does not lock up? I know we just tested about 3000 files and it was taking a while, so this might be the cause.
Indeed, it is the amount of Files that makes this Activity slow.
I have about 70 Devices, Files from 1.1.2010 to be deleted, over more than 60 Directories, sometimes more than 7000 Files in a directory.
the hole took about 3 hours.
Running the same Activity again used 15 Minits to complete (without having to delete somting).
so, I just had to be patient :-)
Good news then - I'm glad it is working better now. Thanks posting back.