All I can guess is you installed originally when both mojoPortal and Form Wizard Pro were using the 1.0 version of ajaxtoolkit, and then you upgraded mojoPortal to a version which uses the newer ajaxtoolkit but did not upgrade Form Wizard Pro at the same time, so the older Form Wizard Pro may have a dependency on the 1.0 version but the file has been replaced by the newer version included with mojoPortal.
Best solution is to upgrade both mojoPortal and Form Wizard Pro to the latest versions available now, which is version 126.96.36.199 of mojoPortal and 0.0.1.0 of Form Wizard Pro.
Since you have not upgraded in a while you may want to read some of the posts in the blog about release notes for versions you have skipped to find out about new features and config options.
Hope it helps,
ps we are within days of making another new and even better release of mojoPortal