Hi,
I am not entirely sure if I am a resident or non-resident, but it seems I may be the former. However, for this year my employer didn't withhold any federal taxes and I planned to file a 1042-S.
Is this a problem/contradiction - to claim tax treaty benefits while filing as a resident?

Many thanks!

Your visa and purpose of visa? When did you enter the U.S. Your citizenship? About your 2008 tax return? Why you need to file Form 1042-S?
What treaty benefits you will get?