Photoshop :: Liquify Tools Tear Holes In Image

Here's a strange situation. 3 of my students have had the Pucker and Bloat tools in Liquify tear holes in their images. I mean really pucker so hard that transparent pixels appear at the liquify point. Their tools were set on the defaults -- not overly strong strength or rate.
 
What gives? All 3 of the culprits were on Windows machines... (Mid 2011 imacs with Windows OS).  The students on Mac had no problem.
 
Oh, also one of the students with the problem was having it so strongly that the Liquify tools were actually creating tiny copies of the whole image *inside* the torn "holes"-- as if the image is being turned inside out! 
 
Edited to add: I've noticed another couple of weird things with those machines having this problem:The Reconstruct tool and Reconstruct button also cause the holes to be torn... but with those tools, the holes are repeated like the run in a nylon.