I use Ulead Video Studio 12...but I never burn from it or any video-editor...but you might check that you have applicable updates installed.
My feeling is that all Video Studio programs I have had (5, 6, 8, 9, 10, 12) have momentary RAM management problems from time to time where the program will freeze while dragging clips. I just close the program and that takes care of it...but it's indicative (to me) of possible problems with RAM management.
Or...maybe the C: partition just needs a chkdsk /r and a defrag.
I don't know, it happens on occasion and I suspect that other users have situations like this.
When in doubt, uninstall/reinstall Corel/Ulead Video Studio
...and install any applicable updates.
You can also check Event Viewer for errors which might offer clues.
How To Use Event Viewer - http://www.bleepingcomputer.com/forums/t/40108/how-to-use-event-viewer/ 0x000000C2: BAD_POOL_CALLER
A kernel-mode process or driver incorrectly attempted to perform memory operations. Typically, a faulty driver or buggy software causes this.
Every video-editor and every burn program...employ drivers. And files become damaged every day, with no warning of such damage.