Perhaps, the feature of AntiDoS is worked because there are too many accesses within a short term.

You'd better disable the AntiDoS function like this:

- Install Protector
- goto Protector's preferences
- set "Accesses counts per a second to warn" to 0
- edit mainfile.php like as the document

And it is danger to run XOOPS 2.0.7.1 as a public site.
You should upgrade 2.0.7.3 or install Protector as soon as possible.