Hi pirx4711,
this is what I had suspected. I can tell you that the abort of replication works well under normal circustances (takes some time as mentioned before) but you suffer different issues most likely related to locking issues of the StoreOnce slots in the Media Agent. At this stage the Media Agent has no chance to intercept. To be honest most of those issues where fixed in the meantime and it is time to check how many of your hot fixes are incorperated into general release patches and prepare for an upgrade. This is the only chance I see.
Regards,
Sebastian Koehler