Well I am having lots of trouble with a simple gallery2 installation with 15 pictures for my wife's hobby pictures. While I am running a 1600 picture gallery on the same server with out any problem touch wood. The back on the main one not there.
And i am having wonderful tech support from dot5 hosting to say the least. The guy does not even know what is Unix he replies it is FreeBSD.
A quick a dirty way to get around. Let's name the site as www.mysite.com Here the user name for your web server is not same as your account. So when you create a file ftp you see the owner/group as "joe/joe" and when web server creates it it is "web/web".
Connect via ftp create a gallery2 directory ; chmod 777 the same on the Top most Document root.
put this file in the same directory "gallery-2.0-full.tar.gz" make sure binary more
also FTP this php file foobar.php with these lines in it
system ("tar -zxvf gallery-2.0-full.tar.gz") ;
Now connect to this foobar.php via a web browser.
Follow the instruction from gallery2 installation when you point your browser to this location
Need to create the g2data directory and chmod 777 via ftp again .
to finish the same Gallery will ask you chmod 755 gallery2 directory.