Cannot preview scenes or project in Windows 8.1

Hi Marisa and welcome to the community!

Ahhh, the 8.1 upgrade - I just went through this process myself. Hopefully we'll be able to get you up and running soon!

First, just please make sure that you're working with all local project files:

• Work on your local drive (your C: drive). Working on a network drive or a USB drive can cause erratic behavior, including file corruption, loss of audio, and other unexpected behavior. 
• You should also make sure the directory path to your project files and your published output is less than 260 characters (for example C:\Articulate).
• Avoid using special characters, accents or symbols in your file names (this includes spaces and underscores).

Additional information regarding "Naming Files, Paths, and Namespaces" in Windows operating systems can be found in the following Microsoft article.

Second, try right-clicking on the Storyline shortcut (from the Start screen, if needed) and select "Run as administrator". This, personally, has solved a lot of issues for me. Hopefully that'll help with the trouble you're running into as well. It seems I've only had to do this once, though, and after that I haven't experienced any other trouble with it.

Let me know if that helps!