Dual Monitor Problem?

Hey Guys,

I have been running dual monitors for the past year or so, and they are great. However, recently, when I turn the PC off and turn it back on again, the icons on the desktop seem to be moving themselves around.

Has anybody else experienced this, and if so, do you know how to fix it?

I installed Ultra Mon a few months back, could it be anything to do with this?

Cheers,

Craig.