App hangs

Hi All.
I am facing a database slowness/hangs in my production environment.Last 10 days I got 3 calls from users complaining about performance(application running very slow or hanging). Once user logs in and app fires up first select statement(very simple statements) it hangs.Not always.As i said we had 3 occurrences in 10 days.Could not find anything in SQl Server Error log or Windows Event Log.App runs on different box.So i searched for solution and decided to run profiler to capture the cause. Once I run a trace in our DEV box and got calls from developers about system performance.So i turned if off.Events that selected are:
and i selected 'Save to table' option.

We have SQl server 2008 R2 STD edition,32GB ram
Now i have 2 question.
1.Why is app hanging and how to solve this problem
2.Why is Profiler drags performance down.

Thank you