emilemma , as you point out:
"...ubu 12.04 and the top most menu that shows the tools option does not display"
But:
it does display inlinux mint debian...
Raise the issue with 'ubu devs' is possibly an option. Their may be a package discrepancy, who knows.
Avast! does it's best to be as broad an AV for Linux distros as possible. As you report it displays properly on Linux Mint.
Did you try using the command Line ?
No quotes:"avast" (Scans "home/user/")
"avast -a" " "
"avast --testall" (Default) test all files, regardless of extension or content (default)
It's actually very fast !