Hi paulw49314826 ,
Could you let us know if you see any error message when Acrobat closes?
Does Acrobat flashes and closes only when you switch between MS Word and Acrobat?
Have you tried with other applications?
Try to perform following steps:
1- Reset the preferences folder- close Acrobat then navigate to C:\Users\Your username\AppData\Roaming\Adobe\Acrobat\11.0 , move 11.0 folder to another location(for example-temp)
To open temp folder,hold down the Windows key and press R on your keyboard>this will launch run dialogue box >type temp and press enter.
If App data is not visible given above, launch Windows Explorer>click on the View tab in the toolbar>then click Options(in the far right),this will launch Folder Options Window>click the View tab>under Advanced settings, find and click Show hidden files,folders, and drives then click OK, then launch Acrobat.
2- If step 1 doesn't work, delete the temp files, in run dialogue box(Windows+R), type temp and hit enter>this will open temp folder, select all the contents in the temp folder and delete, restart the computer and then launch Acrobat.
3- If step 2 doesn't work, find and launch Eula.exe, navigate to C:\Program Files(x86)|Adobe\Acrobat 11.0\Acrobat,launch Eul.exe and accept the license agreement.
4- If step 3 doesn't work , try to enable admin account and then login into admin account and launch Acrobat.
Visit this link on how to enable built-in admin account in Windows: https://support.microsoft.com/en-in/kb/555910
Let us know if the above given steps worked.
Thank You,
Shivam