[Deceptor]

Hi star,

Don't worry about the mass of posts, just glad you can provide me all this information to help you diagnose the issue

Firstly, regarding the "cache collisions", I understand you've set alternative prefix's within vbulletins config.php - however that prefix is only used by vBulletin. vB Optimise has its own prefix within the main settings (default is "vbo_"), make sure those 2 are seperate on your forums and the cache collision should go away.

Secondly, regarding the mod invoking the "maxloggedin" issue. I'm afraid it could be any, mainly those that interface with the datastore itself (most probably). You could try backtrace the error the root of the cause but that'd be tricky - the simplest method would be as you said, trial and error until the error goes away.

If there's anything I missed out let me know, those 2 seem to be your main current issues