Visual Assist is not compatible with Parallels MacLook. Known issues include unintended window resizing and poor performance.
If you use Visual Assist inside a Parallels virtual machine, disable MacLook entirely as described in this Parallels article:
http://kb.parallels.com/en/6858
or install Stardock MyColors and disable MacLook on a per-application basis:
http://www.stardock.com/products/mycolors/