Please provide which dot version of acrobat & OS installed on your system.Please check if any update available for the software going through Help >check for updates.
If its up to date check after repairing the software & see if you are still facing the crashing issue while saving as "Reduced Size PDF".
First of I would like to thank you for the reply. The unit that I'm running adobe acrobat is Win 7 Pro. SP1. Adobe acrobat XI standard is Version 11.0.14
Please try following steps:-
** Restore Preferences :-
1.Choose Start, type reg edit in the Start Search,and then press Enter.
2. In the left pane of the Registry Editor, navigate to the following key: HKEY_CURRENT_USER/Software/Adobe
3. Remove the Acrobat preferences registry entries.
After that please check the compatibility for acrobat standard, if compatibility is checked please make it uncheck & run acrobat as administrator.If the application still crashes open Acrobat, navigate to Help menu & repair the installation.