Hello, I ve had this happen before as well, so dont panic....

Now it is one of 2 things what you need to try first is removing dvdsanta and all traces of it, but only if your using the demo version, if your not DONT do this....go to add/remove and remove it...after all traces have gone re-download the demo version....

If this still happens or if you have the paid version, you have downloaded a file thats corrupt in some way you need to find which one it is and delete it, as santa wont let you access it...

I hope this has made sense lol
If you need more help dont hesitate to ask.....