We have had this happen several times. This sounds insane, however if you log out, while a ghost, log back in, then once again log out/in, it will clear the bug. We had this happen to two people last week, and this fixed it in both cases.

Thanks for the responses! Much appreciated.

Regards skipping Hydross, you can also avoid Hydross' trash completely by sending in a warlock, a priest, and a shaman before the raid (or just a warlock, a shaman, and one more if they have Noggenfoggers for the slow fall effect). The priest levitates down, resses the other two (without clearing any trash I believe the fall to the water is sufficiently far to cause damage and break water walking) across to the nearest pipe (multiple resses required to do this) where the shaman puts water walking on everyone and then the three walk to the pipe between the first and second Lurker packs. Summon raid. Clear packs. Voila Lurker.

Do one better... send a Paladin along.

-Shaman Waterwalkings everyone
-Pally BoPs the Warlock and the warlock jumps, taking no fall damage.
-Priest or mage floats down and runs over
-Pally does his personal bubble and runs over.

You don't need noggenfoggers if you just use pally blessing of protection

edit: beat me to it by half a second

I believe the rez bug can occur if this takes place:

Someone dies inside an instance and they release.
A rezzer casts ressurrection on them before they zone in.
The dead person then zones into the instance with the rez dialog still present on their screen.

I believe that at this point the person will no longer be able to be rezzed inside that instance until it is soft-reset. I have tested this and seen it happen in a couple of zones.

edit;
will try that one out.