Thnx... I did consider your suggestion and used tab Deselecting event.... Thnx again...

I think the codes should like this: private void Form1_Deactivate(object sender, EventArgs e) { this.Hide(); }

Might worth trying: Try sending a WM_VSCROLL message, using SendMessage() (via PInvoke) to the PDF Reader's Handle, when the button is clicked. Should look like this: SendMessage(adobePDFReaderHandle, WM_VSCROLL, (IntPtr)1, IntPtr.Zero); // this should scroll down Hopefully the handle of the control is provided...if not, you'll have to search it... Otherwise, try restoring the focus to the Adobe PDF Reader Control before sending the key combination.

CodeProject is your friend: [^], [^]. For an old (but still relevant, imho) caution against using the PictureBox to pan and zoom: [^]. If you seek to aid everyone that suffers in the galaxy, you will only weaken yourself … and weaken them. It is the internal struggles, when fought and won on their own, that yield the strongest rewards… If you care for others, then dispense with pity and sacrifice and recognize the value in letting them fight their own battles." Darth Traya

Did just that as you said now, Removed all the SerialPort.Close() No change, output is good, but the application freezes after a while. When i try to make the terminal as earlier without event handler i am getting a perfect output with ReadExisting() But using the eventhandler, it just doesn't work as expected

thanx for the reply... secondform.close(); this code worked

I vote for your "2nd form" becoming the main form. It's what you actually want to see anyway. The main form can create and show what now is you "1st form". But it essentially is just a dialog to set up some properties. So make it just a dialogue that is started by your main form. Additional benefit: Later, you can implement a menu, button or whatever control so user can open a connection properties dialogue again, with the same logic you already have (in case user entered wrong parameter, or another controller on another port, or...). Ciao, luker

If you look at the OP, there are two sections of code: the first using SerialPort is the one he has problems with, and the second is labeled as a test to prove the serial port works. The only instant messaging I do involves my middle finger.