I also have this problem. Not sure if switching monitors (I have a laptop with a broken screen, and usually get Internet at a library or school since my home access is erratic) or going to sleep (as when the lid is closed) triggers it, but disappearance of the cursor is consistent in the respect that it occurs most times the computer is on for a while, and is usually accompanied by disappearance of desktop icons (but not background), and the Panel. To my limited knowledge this indicates a glitch in X.
Due to the disappearance of said items, all I can do at that point is open a terminal by right-clicking on the desktop and selecting 'Open in Terminal' (while the cursor is invisible, it is still there as can be evidenced when I click 'control' and the little flashy thing appears (I enabled it in mouse settings)) and from there restart the system, which fixes it but interrupts what I am doing (I can see that programs are still running when I press alt-tab (and an interesting thing is that all running programs are shown there, whereas normally it would just be the ones in the current workspace), but they do not appear when I use alt-tab)...OR I can restart X using control-alt-backspace which presents me with the login prompt after it is done restarting X. This seems to close any open programs and is thus equivalent work-flow-wise to restarting the computer except that it does not actually restart it; all the above problems (panel, icons, etc) are fixed except that the cursor is still invisible.
Even telling me (and I suppose by extension bennypr0fane) what specifically to Google for would be very helpful.
And I second his question about whether system details can be included in a profile.
[Edit: forgot my system details. Running Nadia, not the DebIan version, with MATE. I am using a trackpad original to my laptop, a Compaq Presario F500.]
[Edit 2: Just read READ: How To Get Help!
(which I should have read before posting, as it says in the little 'Forum rules' information box above the post submission form), specifically "Do not resurrect support topics older than 6 months, outdated information can cause issues with newer releases." Oops! Sorry. Please disregard this post.]