This happened in Avast 7.0.1407, after a day, and i have updated from the interface of avast, it gave a black screen and did not load the windows 7 after the welcome screen.
I had to get into safe mode and use System Restore to reload windows.
then I went back into safe mode to uninstall avast 7 with the avast uninstaller.
I installed 7 again, let’s see if the problem happens again.
for you your problem . first add your system info by avast’s new feature in maintenance → support then tick → basic info , log files and minidumps and upload it umm http://www.mediafire.com/ is fast for file uploading and then post your mediafire link here !
No, there is also a Black one. Happens as he said after the “welcome” screen. Sometimes you can wait it out, other times not, just Google something like “black screen at boot” for more on it.