Is it only me or has anyone else experinced flashing when this program is running. Are there any reasons for it.

No, almost everyone.Turn off Render to Texture in your FS04 display settings.Edit: The "other" payware weather program does the same thing.Hope this helps,JimActiveSky Support

Also, the write-up on FSUIPC 3.08 states it has fixes for window priority and focus problems that may relate to this. I use FS2K2 and some of those fixes apply to that as well.

Just tried it. A secondary effect of this is that some clouds are missing which rather defeats the purpose of a weather program. Goes back to what I say that the default weather is better than that of this so called weather program.Not sure if it does cure the flashing as when I tried the simulator with it turned off OR on I never had the flashing. So not sure it even relates to the rendering.I did expect to see a frame rate increase with this turned off but strangeley I never.