I'm running XP Home with SP3 and FSX with Acceleration -- but I seem to recall having the tooltip text problem on portovers as far back as FSX SP1. It seems to be happening with every portover I have, but not with Accel/SP2 native aircraft.
The corrupted-font issue occurred to me late last night just before I'd gone to bed. Are the fonts specified in a .cfg somewhere, and might it be possible to just specify a different font by editing the file? Just an idle thought...
The Fonts are called in exact locations 'in' a gauge and 'in' a particular gauge string. Models do not have the ability to have a font called for. Models meaning, not a gauge, but a part or a 3D gauge (animated parts). Their tooltips are hardcoded with the stock FSX font. But gauges are definately 'optional' and dialed in (if needed/desired) by who makes the gauge code. But, I havent heard of someone changing Font in daytime to night time zones, and I wonder now 'if' its possible to change the actual 'tooltip' font itself, as that might be hardwired into FSX.
It 'might' be available and reassignable in the FS config file. You may even be able to 'add' an entry to the config file (if there isnt an entry for Font type for tooltips in the FS config file), and assign it a new Font, test the new Font, until you find a Font that works properly with your sim.
I remember in Beta testing FSX, that there were alot of problems with some peoples computers with reading tooltips. Some computers were almost locking up with tooltips. I wonder if this could be a graphics driver based issue? This would explain how this happens with updates
Bill