Yup! Happens to me too. Only 1.5 though. I downgraded to 1.0.7 and it went away - but then I realized that I wouldn’t be able to open anything I made in 1.5.
I can have lots of instances of VItal open - such as in old projects, possibly made in 1.5.4 - but if I open the plug-in windows and start adding even a moderate amount of modulation, it invariably freezes and I have to reboot.