I am also having the same issue.
I am using IOMAD on windows. Version details are given below
$version = 2013051404.01; // 20130514 = branching date YYYYMMDD - do not modify!
// RR = release increments - 00 in DEV branches
// .XX = incremental changes
$release = '2.5.4+ (Build: 20140117)'; // Human-friendly version name
$branch = '25'; // this version's branch
$maturity = MATURITY_STABLE; // this version's maturity level
It seems repeated redirection on same file i.e. /admin/index.php at line # 484 (given below)
// Now we can be sure everything was upgraded and caches work fine,
// redirect if necessary to make sure caching is enabled.
if (!$cache and !optional_param('sesskey', '', PARAM_RAW)) {
redirect(new moodle_url($PAGE->url, array('cache' => 1)));
}
Regards,
Krishan