AVG Shell32.dll changed - Spyware, MalWare, Virus?
It is normal. While scanning if AVG finds that the MBR or Boot record has been changed then it AVG antivirus shows those files. This happens during normal maintenance, when you or windows updates files or have had to correct errors on the hard drive. If it dose not show infected then you shouldn't be worry about it.
How to get rid of this message - AVG Shell32.dll changed?
If you don't want AVG to show this message again, you will need to open AVG test center then press F3 function key on your keyboard for AVG to accept the changes. You will not see the message next time AVG run the test. In case for some reason the F3 key doesn't remove the changed, you can also run a search for the file AVG7QT.DAT [by default this file is stored in the root of C drive - c:/] and delete it. AVG will take care of it next time it is run, will rebuild the new one.
Note: This is not for each and every file, some files like user32.dll, shell32.dll, ntoskrnl.exe wsock32.dll are exceptions.