Problem solved. I did a few things, one of which must have sorted things out, but which one it was, I have no clue. what I did:

Reinstalled Direct X, reinstalled FSX SP1 and SP2, reinstalled my graphics drivers, and finally reinstalled the Weather Radar.

I like the radar gauge, but it does appear to have a few glitches:

It still doesn't work on the Ariane FSX 737 though. It refuses to show up on the FSX menu when you add the gauge to the Ariane aircraft. It also appears to screw up the mode control panel on the default FSX 737 and 747 when you install the gauge. The mode control panel doesn't work now in the 747 (either in 2D or VC) and the digits from the MCP on the default 737 have gone missing. this occurred to both aircraft right after installing the gauge, and even uninstalling the gauge doesn't fix it.

Al