From your admin folder (local's end - not server), edit your .htaccess file

from:


# Fix certain PHP values

#<IfModule mod_php4.c>
# php_value session.use_trans_sid 0
# php_value register_globals 1
#</IfModule>

# to turn off register_globals
# php_value register_globals 0
to read:

Code:
Fix certain PHP values

<IfModule mod_php4.c>
php_value session.use_trans_sid 0
php_value register_globals 1
</IfModule>

to turn off register_globals
php_value register_globals 0
Then, save your .htaccess. Once saved, upload that file under your admin folder on the server-side.

Last step - clear out all your cookies and temp files from your browser. Then, retry your admin session activities (preferably with mozilla firefox - not with IE).