Debian :: Iceweasel - Gmail Account Opened And All Windows Show Blank

in the past i always used debian for servers only (mainly webservers, routers and antispam gateways), but now i have to develop some application for linux so i installed it on a desktop (have always been running windows on my desktops). i am running testing (mainly because i need some more recent packages and working with stable i find myself using backports most of the time). now i have seen that the standard used web browser is iceweasel (which according to sources i found is a firefox fork) but this browser seems to have some troubles:

- videos : always gives me an error in the video frame and i have to clear my cookies and reload the page to make it work for every single video i watch. embedded ..... vids work fine.

- gmail : as soon as i open my gmail account on any tab or iceweasel window all other windows are unuseable (show blank as if the application crashed) but gmail works fine. as soon as i close the iceweasel window where gmail is running all other windows are doing normal again.

- lots of pages display very poorly on iceweasel (misplaced div's, ... etc) : this is nearly always on pages where you find overlayed advertising in div's so i guess this is mainly dued to poor coding of those junk adds (i can live with that).

is there any alternative to iceweasel. especially the gmail part is very annoying, the rest i could live with (but prefer not to). i googled the web for those problems but i mostly found that these problems occured because of some extension (for example : ad blocker) but i don't use those so it didn't solve my problem.