Vulnerable contents

I am trying to update to WP 3.3.2 – I get this message – Fatal error: Cannot redeclare class WP_Upgrader in /home/writefor/public_html/BlogClickProfits.com/wp-admin/includes/class-wp-upgrader.php on line 23

I am not a technical person – how do I fix this – also – I was prompted to check all my sites for updates, etc. because my hosting account said my sites are spamming – and I should check with WP support to find out if I have vulnerable contents on my sites. I am in the process of adding the TimThumb plugin and running scans – will that help? I cannot afford to have my hosting account suspended for something like this.

Any help you can offer would be appreciated.

Thanks