NOVEMBER 2015: Running WinXP PRO SP3 2002 TOSHIBA SATELLITE U400 ( old I know ) I keep getting this error: "This add-on ( video download helper )could not be installed because because Firefox cannot modify the needed file" Hi over the last week or so I have installed and had to uninstall Firefox at least 10 times. Older versions 36....to 42.0. IN MANY CASES START PAGE WOULD COME UP BUT BE TOTALLY INACTIVE. In other cases i.e. V 38 would state that my system requires XP SP2 or higher...well I already have SP3?? I have previously had Firefox installed on this computer over the years and have to uninstall whatever version I had at the time because if the infuriating and PERSISTENT BUGS!! CONSTANT bugs!! Never experienced on CHROME or OPERA. Any way just when everything "seems" to be going "ok"......and I go to ADDONS then search and type in "video download helper" then download and then install I get the faled to install because....."Firefox cannot modify the needed file" I keep getting this error: "This add-on ( video download helper )could not be installed because because Firefox cannot modify the needed file" I reckon I have tried every FAQ section in Firefoxs' archive and NOTHING!! I is not a "video download helper" issue at there end. Have had it before so I know it does work and does exist and it does work along side Flash whatever....and I have found DLHELPER to be the best product out there for me. Thank you