Thanks for your post.
I'm not initially sure of what's happening here. Just to confirm, you have a timer in your app that ticks every 30 seconds or so. In the timer tick event, you check something to see if a user is logged in.
When you profile, it all works okay until the first timer tick, but you don't see any information logged after that at all? If so, then does the profiler still seem to be attached after the tick, or has it stopped profiling/disconnected? Does your application continue to respond as normal?
It may be worth having a look in the logfile to see if there are any messages as a starting point. You can access this from the Help menu.