HELP! Scan went awry, I uninstalled Avast, & now it won't reinstall

[suzyq]

I did a full scan of my computer and Avast free (6 I think)  found 20 infected files.  I was given the option of moving these "rootkits" to the "chest" or deleting them.  I made the mistake of deleting them, and after rebooting, a message said "Avast didn't start correctly" or something like that. (The same thing happened with my QuarkXpress program and also Adobe Reader. I haven't dealt with those problems yet.) 

So I uninstalled Avast, and every time I try re-installing it, it starts to install, then immediately uninstalls.

I tried using Avast's uninstall utility, and even though it says it has removed the program, the same thing happens when I try to reinstall it.  Avast no longer shows up in the control panel list of programs to uninstall, but somehow something is preventing a fresh copy from installing.

Can anyone figure out what happened, and how I can fix it?  I don't want to put a different antivirus program on there yet because I'm afraid that could complicate matters.
 
I also don't know why/how it affected Quark, and whether I'll have the same problem.

Thanks for any help you can give me!!!!!

[aztony]

When I upgraded to V7 a couple of nites ago my pc locked up and I had to do a manual reboot. After restarting the system would lock again, and did so after several reboots and restarts. I ended up booting into safe mode and uninstalled avast!, and used two cleaner utilities to scrub any remnant files. Then I rebooted in normal mode and downloaded V7 and saved the file to my download folder. But it would not install that way. I had to use internet explorer to run the installation and I was able to successfully install the program that way.

[Lisandro]

See http://forum.avast.com/index.php?topic=94514.msg752850#msg752850