Some things need to be fixed here, else it is impossible to do a fresh install of 7.5.

in install/createtable.php


find:
PHP Code
USER_NOTIFY_MULTI tinyint(1) unsigned not null default '0'

and replace with:
PHP Code
USER_NOTIFY_MULTI tinyint(1) unsigned not null default '0',

delete this next chunk (it is trying to create PROFILE_COMMENTS again):
PHP Code
// PROFILE COMMENTS TABLE
$query = "																 
create table {$config['TABLE_PREFIX']}PROFILE_COMMENTS (			   
	COMMENT_ID int(11) unsigned not null primary key auto_increment,   
	PROFILE_ID int(9) unsigned not null,							   
	USER_ID int(9) unsigned not null,								  
	COMMENT_BODY text,												 
	COMMENT_DEFAULT_BODY text,										 
	COMMENT_MD5 varchar(32),										   
	COMMENT_TIME int(11) unsigned,									 
	INDEX profile_ndx (PROFILE_ID),									
	INDEX user_ndx (USER_ID),										  
	INDEX md5_ndx (COMMENT_MD5)										
) TYPE=MyISAM														  
";																		 
$dbh->do_query($query,"{$config['TABLE_PREFIX']}PROFILE_COMMENTS table created.");

Note that this code chunk is the second instance of the code that tries to create the table. It is slightly different than the first one so you should be able to easily identify it. (Looks like it's missing some syntax at the end.)