I’ve had this problem with Putty on and off for years. It’s default black background commonly hides the windows text cursor when the mouse rolls over the terminal window. When this happens I need to rummage around on the internet to find a solution, so I thought I’d make a note of it here on my blog this time instead.
The problem is that Putty tries to invert the colours of the cursor, but the Windows default text cursor doesn’t play nicely.
To fix the problem change the Text Select cursor to something else:
Control Panel -> Mouse -> Pointers -> Text Select
Just browse the cursors and pick one you like the look of, I like to use “beam_r.cur”.