I'm having the same problem as everyone else. I've been using Avast Free basically every since it came out, so for years. Have "never" seen this error nor do I believe I need to download a 69MB file to fix it. To me, that's crazy. This is clearly an Avast issue, one I hope they fix very shortly, which I believe they well. Too many over very good "free anti virus" programs out there to have Avast get a bad name over this one.
I'm using the same version, 7.0.1466 and 121003-1 as every one else having the issue. Running on Windows 7, 64 bit, Alienware powerhouse of a PC. I know this issue has nothing to do with my PC, especially seeing everyone else is experiencing the same darn issue. I'll trust in Avast to fix it. If not by tomorrow, I'll be going to AVG, sorry!