Ok, it stopped again after 590135 files.
I have attached the last part of the scan report but I suspect it's the last line that's relevant so I''m just pasting in the last few lines here ...
C:\RECYCLER\S-1-5-21-1202660629-602162358-725345543-1007\Dc712.exe\{app}\fmod.dll
C:\RECYCLER\S-1-5-21-1202660629-602162358-725345543-1007\Dc712.exe\{app}\Narbacular Drop.exe
C:\RECYCLER\S-1-5-21-1202660629-602162358-725345543-1007\Dc712.exe
C:\System Volume Information\MountPointManagerRemoteDatabase
I suspect the last line means something. It might be worth adding that I've added an external usb drive since the last time I run a sucessful scan. Is it possible Avast has got to the end of the C drive and is having trouble switching over to the external drive? Avast was set to just scan local drives.
Also, How does Avast calculate the percentage completed? Is it the number of files checked against the total number of files on the system?
Thanks
John