Hello,I am not sure on this one but have you tried another keyboard?

Have you assigned any keys to a function?

yeah already tried a new keyboard
c is in most game crouching exept wow i cant chat properly

So another keyboard does the same thing?

This could be an assigned key problem?

If its C key on another keyboard then I do not think the key is sticky.Have you tried cleaning the keyboard?

This happens only in the chat?What if you opened say note pad and typed or tried to send an email?Does it do same thing?

Have you updated drivers.I am a little lost on this fix.

i tried all the things this happens only ingame.
when i press shift c then the key does work ingame.

Sorry lippy I am lost lets wait for another tech and see if they have an answer.

But look into this idea I know it is for assigning a key but check if there is a assigned key that can be unassigned?

1.Click the Start button, point to Settings, and then click Taskbar (or Taskbar & Start Menu).
2.On the Start Menu Programs tab, click Advanced.
3.Use the right mouse button to click the item to which you want to assign a shortcut key, and then click Properties on the menu that appears.
4.Click the Shortcut tab.
5.Click the Shortcut Key box.
6.Press the key combination you want to use as the shortcut for the item. For example, press the CTRL key and the F4 key to assign a shortcut of CTRL+F4. 7.Click OK.

Or like my wireless Logitech keyboard has its own key assignment software?