Text editor cursor disappears sometimes.
 

Using: Ubuntu (Lucid) / Gnome (desktop PC not laptop).

EDIT: Just to be clear when I say cursor I am not talking about the mouse pointer but the blinking cursor which shows your current text entry position when entering text.

Sometimes when using a text editor the cursor suddenly disappears. After this has happened using the arrow keys to move the not-there cursor also does not work. I can however click on the document with the mouse pointer and enter text wherever I just clicked even though the cursor is still not displayed. This has happened with both Gedit and with a light-weight text editor called Leafpad. The only way to restore the cursor is to close the editor and reopen it, then it works again. This has happened about 10-20 times over the last few weeks, so not that regularly but it is very annoying.

Any ideas how to fix this?

Many thanks.

Check Mouse Preferrences Settings
 

Check your Mouse Preferrences Settings.
There may be a setting which causes the mouse pointer to disappear when you have not used it for some amount of time during which you only used the keyboard.