I just replaced Firefox (Install Version) three days ago with Firefox Portable 8.0.1 from http://portableapps.com/apps/internet/firefox_portable -- The preferred location to secure Firefox Portable.
Firefox Portable is "trouble-free" compared to the corresponding Firefox 8.0.1 (and prior) installations, and with virtually no "unresponsive javascript" messages.
There are (2) Sticky Password Build 505241 glitches:
[1] SP Autofill "unresponsive script" is the only script-error experienced with Firefox Portable. Whereas, SP Autofill unresponsive script has shown up frequently under the past few Firefox install versions.
[2] SP Autofill Plug-In must be re-installed after every computer re-boot. The Process -- Click on the SP "X" Caption Button THEN click on "Sticky Password Autofill Plug-In not installed THEN exit Firefox Portable while the plug-in quickly installs THEN reload Firefox Portable. This recurring glitch is actually quick to re-fix for each operating session -- But this should not be necessary.
SP's Caption Button in SP Settings correctly shows both Mozilla Firefox and Firefox Portable to be installed in Sticky Password at all times, regardless of Autofill's working status, before or after, Autofill's computer re-boot and subsequent re-installation.
