Issues with plug ins no longer functioning

Hi all

I am having strange issues with my site since downloading the latest version of WordPress (2.9.1), various plug ins including Gig press, post tabs and competition manager. I have been running gigpress on my site for quite some time but it seems anything that requires code such as [competition_12] just won’t work and displays the code as though it isn’t recognised, please see link for an example https://www.brightoncalling.com/wordpress/?page_id=1209

Can anyone shed any light on what is happening?

Many thanks

Lily @ Brighton Calling
https://www.brightoncalling.com/wordpress