system
6
There is no separate frntpage.htm file. It is data defining that document within the msoeres.dll file; that is, the page gets extracted from that DLL file.
See http://windowsxp.mvps.org/oescript.htm for information (found just by Googling: http://www.google.com/search?q=“frntpage.htm”). It certainly appears script blocking now added in v6 of Avast could be causing the problem but it also looks like you can undo the change it made to the Internet security zone settings.
UPDATE:
I just installed v6 and did the required reboot. The “binary and script behaviors” option for Internet Options did not change from before. It was Enabled and still is. If this option got disabled, maybe you have some other security software that made the change. I also started OE6 after the Avast v6 upgrade and reboot and it doesn’t have the frntpage.htm error that you reported.