My cursor will sometimes jump to some unintended location while I am moving it.  I have inadvertently closed windows before realizing that the cursor had jumped from a location in the document to the "X" in the upper right hand corner.

   I would suspect the problem to be with the mouse especially if it is wireless.  Cheap wireless mouses will do that from interference or when the battery is low.

What type of mouse? What Operating System?

I had similar problems with a Microsoft mouse, finally had to discard the mouse. I believe it to be the fact that the grandchildren continually banged it on the desk out of habit because their mouse always had a dirty ball, trouble was mine was optical.

I purchased a Logitech wireless, Very pleased with the performance. But has a problem when booting from a Acronis True Image CD, the drivers are not available, I use a cheap PS/2 mouse when I take a disk image.

I am using w98 and have the same problem.  I changed the mouse twice and it didn't make any difference.  I still have the problem and guess I will till I get a new computer.

   I have had a Logitech wireless mouse and it has worked very well for me.  Before that I had purchased a cheap wireless and it had all kinds of problems.
   To me it seems that there are only two possible sources for that problem: the mouse or the motherboard.  A bad motherboard usually acts differently (like the mouse not working at all) but since you have tried two different mice and the problem still exists, that only leaves the motherboard.
   Maybe someone else knows more about this.  If they do, please jump in at anytime.

We are using IBM computers and mouses where I work.  I have a Logitec TrackBall and we all have the same problem.  Seems to jump back when you are trying to select a sentance and you only get part of it.  Thought it might be something to do with Office 2003.

This could be a software problem. Nearly all mouse software has a setting to make it jump to a default location.
Perhaps the software has become corrupted, or you may have the wrong software installed. Windows treats everything as a Microsoft mouse unless you install other software.

I have a Logitech Laser wireless mouse. I had the same problem to start with: It says that the mouse controller ie the receiver can be fitted to an USB port. Can and can, but the drivers are not good so it did precisely what you are describing. Then I put it as a PS2 mouse with normal inlet and voila it works just perfect!
Have a nice day.

   I have a Logitech Laser wireless mouse and it is hooked in on USB and it has no problem.
   There are two different USB formats the old USB1 (often just called USB) and the new USB2 (sometimes also called USB but usually somewhere they mention the 2 part).  They use the same connection but a USB1 is much, much slower than USB2.  Maybe your mouse is expecting USB2 and you have it hooked into a USB1 port on your computer.  This would cause the data exchange to be much slower and I can see how it would cause the cursor to jump.
   PS2 is the normal round connection for the mouse.  You can get a little connector that goes from the USB to PS2 so that you can connect the mouse into the normal mouse port.  I take it that is how triuno connected it into the PS2 port.