heres an image when i click [see full list] of my online users
That seems to be an issue with the server, as the current time is being reported as -INF (minus infinity). That shouldn't be happening
A. admin panel --> configuration --> settings --> Who's Online --> Cut-off Time (mins) <-- what do you have here ?
do you have a numeric value here (eg. 15 OR 30 OR 60 ..)
B. run file verification tool from tools & maintenance section to check for changed / missing files