i try to setup xoops in windows 2003 but show this message under the setup box! so, what can i do to fix that?

PHP Warning: session_start() [function.session-start]: open(C:\DOCUME~1\avuser\LOCALS~1\Temp\php\session\sess_aonbulfboc2n1uist7snt686o1, O_RDWR) failed: Permission denied (13) in C:\Inetpub\wwwroot\install\include\common.inc.php on line 40 PHP Warning: Unknown: open(C:\DOCUME~1\avuser\LOCALS~1\Temp\php\session\sess_aonbulfboc2n1uist7snt686o1, O_RDWR) failed: Permission denied (13) in Unknown on line 0 PHP Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (C:\DOCUME~1\avuser\LOCALS~1\Temp\php\session) in Unknown on line 0

It seems your internet user (I_USER_xxxxx or something, that is the alias for anonymous users) has no rights to write to the temporary space for session files. (See error message for the location)
Check the permissions for this directory and the internet user and the documentation for the PHP install of ISS.

I have server! and i am admin in this server! so i change local path permission in default web site to write, read, log visit, index this resource in IIS and try to setup xoops! But i cant...

Permissions are twofold, once in IIS and once in the filesystem. Observe that the correct user(s)(groups) have the right permissions.
You may find some helpful threads by searching for IIS.

I edit season.path in php.ini file :) and slove this problem.