Split screen in fs9 with fs Navigator

[nichos]

Asus A8N sli nforce4
AMD 64 3500+ (2.21mhz)
1gb ram
Asus A8N sli nforce4
AMD 64 3500+ (2.21mhz)
1gb ram
Gfx card: NVIDIA GeForce 6600 GT 128mb
160gb Sata HD.
WinXP SP2
FS9 - fs91update

FSNav 4.7 problem,


When I run FSNavigator a split screen occurs in the top halve of the screen, same hight or debth as fsNav window when set to top RH corner, FS9 flies in the top part of screen, whilst the bottom halve and instrument panel freezes. fsNav carries on flying.

It is a random occurence, and difficult to determine what causes it.

Only happens with fsNav displayed and not with any other extra window diaplayed, ie. GPS, ATC etc.

Note in foto aft strait & level, with horizon still showing previous bank, at moment of split.

Tried various nVidia drivers 71s, 77s, 78s & 81.84 but cures the problem.

Any help will be grately appreciatd, nick