Even with Mouse.Visible=false, the mouse cursor pops up when dialog options are displayed at the bottom of the screen, although it won't move. It goes away again after an option is picked.
What type of dialog options display are you using? (custom / Text Window GUI / default?) Are you using DX5 or D3D graphics driver?
Default one, DX5 driver. Doesn't seem to happen with the D3D driver.
Ok thanks, I've reproduced this and will fix it.