I had a client report to me that their Adobe Reader client on Windows XP would crash upon trying to open a PDF. I assumed they might be dealing with a malformed PDF but I was able to open the file as an administrator. With that information, the problem could either be tied to her non-privileged account or to permissions. I wiped out her preferences stored in the HKCU registry and her files in Application Data\Adobe and Local Settings\Application Data\Adobe. This move allowed Adobe Reader to open when launched from its shortcut but it would crash as soon as you tried to open a PDF or if you opened a PDF directly.
At that time, her Adobe Reader was a version behind. I downloaded and installed the latest Adobe Reader and it began working properly again. I restored the things I had (backed up and then) wiped out and it still worked fine. About a month passed with her using Reader on a daily basis and suddenly it broke again in the exact same manner. I found the following details in the Event Log.
Application Error
Event ID: 1000
Faulting application acrord32.exe, version 10.1.1.33, faulting module unknown, version 0.0.0.0, fault address ox00000100.
I couldn’t find any successful solutions online and ran across the error with another user. Through sheer blind luck, I managed to dig around in the HKey Current User registry settings and found a setting for Protected Mode. The standard user account doesn’t receive the popup like an administrator does to choose whether to open with protected mode disabled.
Under HKCU\Software\Adobe\Acrobat Reader\10.0\Privileged, there is a key called bProtectedMode. It was set to 1. I switched its hexadecimal value to 0 and Adobe Reader immediately began working properly for the user. I carried this solution over to the original client (whom I had setup using a portable PDF reader in the meantime) and Adobe Reader began working there as well.
I’ll still give more credit to luck than to my troubleshooting/diagnostic skills but it sure was weird to be able to fix the error in this manner. I’ll just have to see how long this lasts and if the setting reverts to ‘1’ if the error returns.
Update: I ran across this error on a third computer now. Instead of crashing hard, the program just closed after two seconds of being open whether you opened Adobe Reader directly or tried to open a PDF file. In this case, the HKCU\Software\Adobe\Acrobat Reader\10.0\Privileged key didn’t exist. I created it and the bProtectedMode value, setting it to 0 (zero), and the application began working fine. The next time I opened it, it prompted if I wanted to participate in the Adobe Reader user experience program.