I've got a wordpress blog, wordpress version 3.3.1

My host is home windows server 2003 with Plesk 8.6

Things are fine during my blog, except one factor: The course pages aren't proven. but almost every other pages, even tags page are showing properly.

I'm giving a 404 Not found error when attempting to gain access to a category page.

This can be a category page : http://2barnamenevis.com/index.php/topics/it/

I've selected this permalink structure because without index.php in permalink and without needed extensions, wordpress can't create permalinks.

Also I've transformed the permalink structure of groups for this : http://2barnamenevis.com/index.php/categories/it/ however I'd 404 error.

Other pages, such as this tag page : http://2barnamenevis.com/index.php/tags/magic-eraser/ are showing properly.

What's the problem?