Check to see if maybe you had used this vst and it crashed and is still running in the background. Ctrl alt delete and look for running hosts. Make sure to try a restart your computer then try outputing the file again. Try changing to a different output folder under File/Preferences/File Location. The typical path for Vst plugins is many times C:\Program Files\Steinberg\VstPlugins try changing it to that. Try outputting it to a different harddrive if you have one.