The log file of the boot time scan should be located here:
C:\Program Files\Alwil Software\Avast4\DATA\log\aswboot.txt.
If you can find it, please copy and paste the contents. (You could also search for aswboot.txt.)
To run a boot time scan with avast! Right click the scanner screen, select 'schedule a boot time scan' and reboot when requested. (Or open the tab at the top left of the scanner screen and select the boot time option from there.)