INTERNAL SERVER ERROR

HI ,
I have recently move my WP site, from one house hosting to another.
This was how I proceed :
1) Backup the database
2) Backup the site files

on the new space. I have regularly installed
WP 2.02 ( like the site before )
then upload all plugin and theme old files,
restore the database,

and seem that all was gone very well

BUT BUT BUT !!!! …..

For some options
for example I wish to change options on social bookmarks plugin, I receive this message :
Forbidden

You don’t have permission to access /wp-admin/options-general.php on this server.

or for edit some old post, for example to add tags, I receive the same message of above.

This not for all post, or all options….

Think, for change some posts, I must work on database….

I really don’t understand where’s the prob.

I wish to informyou about another thing…

just for try, I have installed another copy of WP, to a sub directory, and after making some changes, I has received the same error from the server….