Unknown icon in system tray

[Yudhajit]

Hello friends,
I have an unknown icon that always appears on my system tray when I start my computer. No left or right click and not even mouse over shows anything. What is it? and how to disable it?

Thank you in advance.

[need Tos]

Check the programs that startup with your computer. To do this (if you have XP) go to Start => Run =>type "msconfig" => click on the "Startup" tab and see what programs are checked. If you're not sure what something is, google the "Startup Item" name. You can find out the icon and the process running.

[Expertz]

I think it may be MSN. There is a feature in MSN where you can hide it by pressing a combination of keys (Shift + M for example), by doing this it creates an icon (like that one you stated) which is not (right/left)clickable (for hiding reasons). If this happens, try finding the shortcut to unhide it, or ctrl + alt + del and end MSN within task manager.
You can also disable this feature in the MSN options.

[Gusgr8]

You can can go to Toolbar =>properties => customize for a list of all the possibilities. You may be able to find the matching Icon in the list.
You can also try this Process Explorer from Microsoft. It's like your task manager but has more info on each process running. It is free and will show you all the processes running on your system.

[Jimmy24]

Go through this thread:
How to remove system tray icon
how to remove unwanted icon in system tray