Hi Joel,

Have you installed the Inventor 2015 Updates and Hotfixes?
Use the below link for updates:
Updates

Also, have you tried running going to the Tools tab > Application Options > Hardware tab, and select the setting to use the Software Graphics. Then close and re-open the file to let Inventor, in order to rule out graphics card issues.


This setting uses Inventor to render the onscreen graphics and therefore any graphics anomalies that exist while using this setting can be attributed to something other than the graphics card.

If the issue returns when you set the option back to the recommended setting, then you should look into updating or rolling back your graphics card driver, or getting a different graphics card that handles Inventor graphic better.


I hope this helps.

Regards,
Lokesh.