I have this problem with just a Kontakt 5 instrument loaded in the rack, so it’s not isolated to VEP. only after they update to 7.5.3. It took a while thought before the symptom started I had cubase open for at least a couple of hours, then it started. Just had to restart cubase for it to go away, but there is definitely something going on under the hood with 7.5.3 that is a little odd. I’m on a mac though 10.8.5 so it may just be a mac issue.