My children started complaining that the Win 7 media center was crashing when they were watching videos. This is a fully patched system. It only started after upgrading to build 6.0.1367 of Avast. Uninstalling and installing 6.0.1000 the crash goes away.
The crash happens when playing content from the users\public\videos folder accessed through media center->Pictures+Videos->Video Library. I pick a .dvr-ms file to play (old content recorded when I was using MCE on WinXP), and let the video play to the end. When the the delete/play windows comes up, MCE crashes with the following error in the event log:
The crash event has the following:
P1: ehshell.exe
P2: 6.1.7600.16385
P3: 4a5bccdc
P4: System.Web.Services
P5: 2.0.0.0
P6: 4ca2bb27
P7: b3
P8: 51
P9: System.InvalidOperationException
Using the real-time graphs Avast has (useful feature) I could see which shield was being exercised. When I added ehshell.exe to the web-shields exclusion list in 6.0.1367 the crash went away.
I've reproduced the crash on a second computer that was freshly installed. I'm posting this here in case anyone else runs into this unexplained crash.