Table 'freepbxdb.custom_extensions' doesn't exist]SQL

I have installed FreePBX on an SME server but when I try adding an extension or trunk, I get

"FATAL ERROR

SELECT custom_exten, description FROM custom_extensions WHERE custom_exten in (‘206’) [nativecode=1146 ** Table ‘freepbxdb.custom_extensions’ doesn’t exist]SQL -
SELECT custom_exten, description FROM custom_extensions WHERE custom_exten in (‘206’)"

The only answer I’ve found so far was from an old post on your forums which said

“uninstall and then reinstall the customappsreg module solved my problem and created the needed mysql data table.”

As I am totally new to this, I’m not sure how to go about this.

(I installed following the instructions found at: http://wiki.contribs.org/Asterisk and http://wiki.contribs.org/FreePBX)

I went and enabled a number of modules and it appears to have fixed it.