Installation Default settings blocking Firefox 13-14 Tools/Options & Downloads?

Hi - apologize if this issue has been addressed previously, but I’ve been having no luck trying to fix a few persistent problems with Firefox 13/14 (unable to access Tools/Options or download/upload/save/attach without it hanging upand I don’t know if there are some AVAST! settings (Sandbox? SafeZone? Something else?) which might be contributing - in addition, both versions of Flash (ActiveX and the plug-in) don’t seem to be buffered; getting a lot of mis-synching and anomalous noises when attempting to play videos from YouTube at that site or after posting to Facebook…please advise? Have uninstalled and reinstalled Firefox Versions 13 and 14 2 times each, as well as both Flash versions…thanks; MUCH appreciated! Jim