Big problem in SiteURL

hi

i have WP 1.2.1 and somtime site URL change automatic and all of link and categories not open foe example my address is “h**p://test.exampel.com/index.php?cat=12” but sometimes is change to “h**p://music.irdesigner.com/wp-login.php/wp-trackback.php/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/wp-admin/index.php?cat=12”
and all of link is change.
can you help me?

thanks