can i install and run, without issues, two different versions of firefox browser on windows 7? obviously they will not be open/running simultaneously - just installed in their own separate directories and running one at a time. (in fact i will mainly run the newer one for daily browsing, which i will update, and use the old one, with no more updating, for some very specific -and no longer maintained- add-on use.) my only real concern, potentially, might be any "shared" stuff that might be happening - if it is. though it may not be an issue anyway because the last directory in the "config" files location structure is always a randomly generated type; \Users\XXXXX\AppData\Roaming\Mozilla\Firefox\Profiles\qa3an0pd.default. issues could happen i think, only, if the "config" location would be shared, which they are not. right? i am thinking this is how having two separate version firefoxes would look like; firefox 5.xx installed under; C:\Program Files\Firefox_5602 firefox 6.xx installed under; C:\Program Files\Firefox_6xxx (or whatever directory names as made by me) both having a separate "config" directory like so; \Users\XXXXX\AppData\Roaming\Mozilla\Firefox\Profiles\qa3an0pd.default \Users\XXXXX\AppData\Roaming\Mozilla\Firefox\Profiles\vs5ar8txw.default (which are auto created by the firefox install itself) so, in theory, if you wanted to, you could have dozens of different firefoxes. i want just two. and i'm asking this just before trying it anyway, in case someone else runs two or more and reports no issues.