While upgrading from 6.29 to 6.30, a friend mistakenly placed the core modules in /sites/all/modules. He ran UPDATE.php and all seemed well. Earlier this week he upgraded to 6.31, this time placing the core modules in their correct location. Now, no matter what he did, the site wouldn't budge from 6.30.

I asked him to delete the 6.30 core files in /sites/all/modules but now the site is down with an error message:

Fatal error: Call to undefined function user_access() in /home/svrpca/public_html/sites/all/modules/lightbox2/lightbox2.module on line 605

Thoughts?