Server doesn't execute WP .php files

Hello.

I have a very strange problem with WordPress. I have a shared hosting account with a WP installed. Everything works fine.

I decided to move to VPS, got one with fresh Debian 6.04, PHP etc. Even the hosting panel is the same. I created a database with the same credentials and placed all WP files to new place. And there is the problem—the server doesn’t execute .php files and a browser downloads them. However, the most strange thing is that a fresh instance of WP works fine here.

I asked support of my VPS provider to check the server configuration and they did. But the migrated WP .php’s don’t work anyhow.

Can anybody say me what should I do?