Photoshop an unexpected and unrecoverable problem has occurred photoshop will now exit

you need your serial number.

if ps cs5 is installed on a pc, you can use Belarc Advisor - Free Personal PC Audit, for software, hardware and security configuration information on your computer.…

if you purchased from or registered with adobe, you might be able to retrieve your serial number from your account, Adobe ID

and before reinstalling, reset your preferences -

acrobat:  http://help.adobe.com/en_US/acrobat/X/pro/using/WS58a04a822e3e50102bd615109794195ff-7feb.w.html

adobe media encoder: https://forums.adobe.com/thread/1713540

after effects:  http://helpx.adobe.com/after-effects/using/preferences.html

dreamweaver:  https://helpx.adobe.com/dreamweaver/kb/restore-preferences-dreamweaver-cs6-cc.html

flash:  http://helpx.adobe.com/flash/kb/re-create-preferences-flash-professional.html

illustrator:  http://helpx.adobe.com/illustrator/using/setting-preferences.html

indesign:  https://forums.adobe.com/thread/526990

lightroom: https://helpx.adobe.com/lightroom/help/setting-preferences-lightroom.html

muse (mac): https://forums.adobe.com/thread/1246022?tstart=0

photoshop:  https://forums.adobe.com/thread/375776

photoshop elements:  http://www.photokaboom.com/photography/learn/Photoshop_Elements/troubleshooting/1_delete_preferences_file.htm

premiere pro: http://www.mediacollege.com/adobe/premiere/pro/troubleshooter/trash-preferences.html

if that fails, uninstall, clean (http://www.adobe.com/support/contact/cscleanertool.html) and reinstall