Exporting

I am having problems exporting to anything.  

The file name pops up and puts an extension .ai on the end, (why??)  and there's ZERO file extensions listed in "Save As Type".  I have Corel Draw 11.  Help!  I can't export to anything!  I have a Book Cover with photos & text, and have tried other files too, same thing.   I need the Book Cover to be turned into a jpg at 300 dpi for the online publisher.  Thank you for your help!