Question about Ontime!

Just a quick question! I checked my ontime and it said that I had logged in 14 minutes. I had been on for nearly thirty so I called BS and decided to turn on a timer. At first the ontime didn't lag along with the timer, but after 15 minutes it just stopped for around five minutes until I logged off. 51 minutes later I had only logged in 20 minutes. So, is there any way to fix this or should I just use a timer?