Problems upgrading to WordPress 2.6.5

After completing the upgrade automatically, I checked the site, and got the following message:

Parse error: syntax error, unexpected ‘!’, expecting ‘,’ or ‘;’ in
/home/xxxxxxxx/public_html/blog/index.php on line 101

I edited the file as follows: (str.charAt(c)!=’!’) changed to (str.charAt(c)!=’;’)

The same message came up for the following files:

/home/xxxxxxxx/public_html/blog/wp-blog-header.php
/home/xxxxxxxx/public_html/blog/wp-load.php

When the last one was changed (/home/xxxxxxxx/public_html/blog/wp-includes/compat.php) the screen was blank when I re-tried the blog.

Any help will be appreciated.