You can try installing the trial version of ZoomText 9.14 from the following site: http://www.zoomtext.com/software/v91/ZT914_T.exe
This should hopefully install some files that should hopefully take care of this problem. I believe you would install the trial but you would use the ZoomText 9.12 version you are currently running. Let us know if it does not work. Another suggestion would be to try and take note of what you are doing that maybe causing this problem. Hopefully we could narrow down what action or program that might be causing this. Also if you get the option to send the ZoomText error log file please do.
I hope the install of the trial helps. Thanks.