I just updated adobe acrobat reader but now cannot open pdf files. I get the msg : A problem with Adobe Acrobat/Reader. If running, exit and try agai. (4:4) This is just after rebooting so no programs are running.
What is your operating system? What is your Reader version?
Can you open Reader by itself? If so, try to disable Protected Mode [Edit | Preferences | Security (Enhanced)].
Did you try running repair for Reader?
Which version of Reader are you using?
Do you see this error in browser? can you launch pdf in application?