What is the error message?
The classical questions...do you have the latest version of QuickTime installed on your Windows 8 64 bit computer and are you running Premiere Elements 11 from a User Account with Administrative Privileges?
a. Also, what are the properties of your source media? What has the program or you selected as the project preset for this project? What is the duration of the Timeline content?
b. Have you used the - + slider of the Timeline to expand the contents there so that you can inspect the Timeline content for slivers left over from deletes or Timeline content maneuvers, transition placement, etc? Those slivers typically present as very thin vertical black lines scattered about the video tracks?
c. What are the specifics of the exports that you have tried...Publish+Share/Computer/??, Publish+Share/Online/?? Other?
But the description of the error message would be the starting point.
Just this for now. Then we can decide what next based on these initial replies. Have you started to explore making a copy of the present project and taking it apart progressively in search of offending component (s) of the Timeline?
>won't let me export from [File]
I think you need to go to the Share option, not export
Saving & Sharing http://forums.adobe.com/thread/1137128
-Sharing to DVD or BluRay http://forums.adobe.com/thread/1137645
-Sharing for Movies http://forums.adobe.com/thread/1051093
-Sharing for Computer http://forums.adobe.com/thread/1058237