I installed Avast yesterday. Whenever I try to execute beta or nightly Firefox installers, I receive error “Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.”
The latest stable Firefox 36.04 installer works as does following:
Installers which do not work:
- http://ftp.mozilla.org/pub/mozilla.org/firefox/releases/latest-beta/win64/en-US/Firefox%20Setup%2037.0b7.exe
- http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-aurora-l10n/firefox-38.0a2.en-GB.win32.installer.exe
- http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-aurora-l10n/firefox-38.0a2.en-GB.win64.installer.exe
- http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/firefox-39.0a1.en-US.win32.installer.exe
- http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/firefox-39.0a1.en-US.win64.installer.exe
- Firefox beta/nightly auto-updates, both small and full.
The problem can be resolved by going to Avast settings → File System Shield → Customize → Scan when executing → Uncheck Scan programs when executing.
My OS is Windows 8.1.