You can download Acrobat X from here: Download Acrobat products | Standard, Pro | DC, XI, X - Just use your old license key.
Here is the bad news: The "now pages selected" error is very misleading and wrong. It seems to be a catch all error that has nothing to do with how many pages are selected. In your case, it seems to be related to you license. One reason why you may get the license expired error is if your computer's time and date is off. Check that and see if you are either running in the future, or in the past as far as Acrobat is concerned. If that does not help, then your only course of action is to get in touch with Adobe's support: http://helpx.adobe.com/contact.html After selecting the product and the problem category, you should eventually see a "Still need help?" button. When you click on that, you should be able to chat with somebody.