It's Win 7 x64 specific, liz. It doesn't affect everyone, and it's not always the same problem, but there does seem to be a problem with 7 x64. On my dual boot machine, Win 8 is fine, but 7 had boot problems with v. 7.0.1456 Free. Once I uninstalled Avast everything was fine. (http://forum.avast.com/index.php?topic=101081.0)
I'm kinda upset about it. I feel betrayed. I hope they figure it out, but from the comments I've read, the question everyone seems to be asking is "what have you done wrong?". There is nothing more infuriating than that.
I had the same issue.
1 desktop, 1 laptop, and 1 HTPC. All 3 running Avast 7 free on Windows 7 Home Premium 64bit, fully updated. The laptop and HTPC are set to auto-update the definitions, and the program. The desktop is set to auto-update the definitions, but ask before updating the program.
The laptop and the HTPC updated fine, automatically, to version 7.0.1456. After the update, they informed me the system needed to reboot to finish the update process. Both machines rebooted fine and have had no issues. I did not have any settings changed (auto join the avast community/reputation services auto-on) on these 2 machines, as others have mentioned.
The desktop informed me there was program update available to update to 7.0.1456. I chose to let it update. After the update, I was again informed the machine needed to reboot to finish the update process. Upon rebooting, the systems hangs right after the login screen. The cursor spins in a circled, thats it. I waited 30 minutes, powered off, and powered back up.... same thing. After another 30 minutes, I booted to safe mode. I wound up having to un-install Avast, then download the full install, and re-install it, and re-register it. It would not let me import my settings from another system, so I had to go in and re-configure everything also. This machine also had the settings changed to "auto join the avast community, and reputation services to auto-on.
So, evidently, there is a definite problem with the manual update to 7.0.1456, as I have read several people with the same issues.
I wanted to make my situation know, that the auto updates worked fine for me and I had no settings changed..... but the manual update dealt me fits, and I had to completely re-install avast.