Upgrade to 1.2 > 404 popup error in admin cpanel

Just upgraded to version 1.2

Each time I go to admin control panel it loads a popup with 404 error, the link it tries to load is:

DOMAIN/components/com_mobilejoomla/installation/index.php

How do I resolve this?

Try to logout and relogin.

In what way do you update MJ, by click on cpanel icon or manually uploading MJ 1.2 package?

Both. The login/logout seemed to fix it.

By the way, what Joomla version do you use? Is it original or patched (in a way) version?

Latest 2.5

it also has Multisites which may have modified some core files.