Media player with custom controls: track bar slider lags

Question

I'm working on a media player with custom controls and it actually works perfectly. However the track bar slider which shows the current position in the video doesn't move constantly in a nice move, but, how should I say, lags every second, or so. The timer interval is 100 milliseconds and the maximum value of the track bar is 2000, so that shouldn't be the problem.

I use the fallowing code for the timer:

        try
        {
            if (W.playState == WMPPlayState.wmppsPlaying)
            {
                tr.Value = (int)W.Ctlcontrols.currentPosition;
            }
        }
        catch { }