I just went through a long, unpleasant process with the new AVAST 7 IS. Up front, I'll tell you it probably wasn't AVAST, but not sure. More likely, it's the dummy at the keyboard.
I have Avast internet security 6. Last evening, I downloaded the new beta, out of curiosity, installing over the top of avast 6 is. I don't normally bother with beta programs. No settings were changed. Almost immediately, everything slowed to a crawl. My web browsers, both Google and Firefox 10 took nearly a minute to open and crawled along. I then tried to open other software, Word and a couple of writing programs, even solitaire and experienced the same problem.
My computer is an old refurbished Dell Dimension, Pentium 4 with Win XP pro, sp3, 2G ram.
I rebooted. No change. Rebooted again. No change. Hard booted, and no change. Today, since nothing had changed, I decided to remove 7 using the system restore point it created. It wasn't there. In fact, system restore didn't work at all. It still doesn't work in fact. All I get is a white box.
I went into Add/remove programs, figuring to remove avast that way and reinstall 6 and got some sort of error message that, unfortunately, I didn't copy. In any case, it wouldn't let me uninstall.
Finally, failing everything else, I used Revo uninstall and had to do a forced uninstall, then went through the computer and cleaned out all traces of Avast. I reinstalled 6 and all seems to be back to normal. Computer is running normally again.
As I mentioned, I won't blame avast. But, I changed nothing in avast 7 and downloaded it from the link posted at the beginning of this thread.