403 error after installing latest version on Joomla 2.5.6

After installing the latest version of Mobile Joomla I am unable to access the site period. I get "403 - Access Denied". This is fresh Joomla 2.5.6 installation. System only seems to work if I turn off the system redirector, but I still get an "Access Denied" message in the mobile version of the site. Any ideas what is going on? What I have or have not done correctly?.

Thanks

Is it really fresh J2.5 installation (that is Joomla+MJ only)?

I have other extensions loaded.

What enabled plugins of "system" type do you have? Most likely there is a conflict with one of them.

Here is the list, I have another site working with Mobile Joomla, I will try and see what is different about the two.  Thanks for the help.

System - Admin Tools
System - Debug
System - Highlight
System - Jumi
System - Jumi Router
System - jVoteSystemDatabase
System - Kunena Forum
System - Log
System - Logout
System - OpenPotion Asynchronous google analytics
System - P3P Policy
System - Remember Me
System - SEF

I mean not only plugins named with "System -" prefix, but all plugins that are displayed after selecting "system" in dropdown box on the right (e.g., it should display "Mobile Joomla!" as one of such a plugin).

Sorry about that,

Mobile Joomla!
System - OpenPotion Asynchronous google analytics
AcyMailing: (auot)Subscribe during Joomla registration
System - jVoteSystemDatabase
System - Admin Tools
System - Kunena Forum
System - jHackGuard 1.7
System - Jumi
System - P3P Policy
System - Debug
System - Log
System - Highlight
System - Remember Me
System - SEF
System - Logout
System - Jumi Router

I compared this to a site that is working with similar pulgins and the only two that this system has is System - Admin Tools and Security -jHackGuard 1.7.  I have tried to disable jHackGuard because I didn't even install it, I guess the hosting provider has it pre-configured, but that did not change anything.  Don't know what System - Admin Tools are so I didn't want to disable that one.

Oh, I am using Kunena 2.0 on this sytem and Kunena 1.7 on the system that is not having any issues.  Hope this information helps.

I have uninstalled jHackGuard and no change.

Seems that "System - Admin Tools" is part of Akeeba Backup component. You can try to temporary disable this plugin and test MJ work.

That was it!!! 

From my research, isn't that plugin required for AKeeba Backup?

Thanks for all you help.