I'm currently playing Scenario 9, Omaha Beech with the latest patch for Windows 7 in windowed mode.
Spasmodically I lose all smoke when a unit is fired on and smoke would normally be generated. The U key will not bring it back but the map appears to be slightly brighter when smoke should be there. I do not know if it will come back normally on the next occurrence of generated smoke.
I notice a similar problem with WinSPMBT. This is the largest scenario I have played both in map size and unit numbers so it is probably a graphics problem.