On Windows 7 Pro pc, had to system restore 4 times; twice uninstalled Avast version 5.1.889. I kept getting a com surrogate error and many of my programs stopped working:
I had the same experience on update to 5.1.889. My Son's laptop did this. quite a few failing executables and services including Windows Family safety, Networx, com surrogate and so on. Tried removing via safe mode and doing a clean install of 5.1.889, but that didn't work either.
In the end had to boot to safe mode again to remove Avast 5.1.889 and then re-install 5.0.677 which I happended to have still around.
Son's Laptop is ACER 1810TZ (intel) running windows 7 Home 64-bit
My desktop had same problem Windows 7 Untimate 64-bit again , but AMD PhenomII.
Then my father called to say his laptop (Toshiba) intel running 64Bit Win7 (Home) was failing. Turned out to be the same thing. All 3 fine when back to 5.0.677
I have rated and recommended Avast to people for a long time, but for me and my family this update was not a good one.