Maybe it's video driver or color setting related?

>I created a VFP 9 application also in XP but the problem persists.
>
>It works one other Windows 98 and newer operating systems except in Windows NT
>Unfortunately, in a one Windows 98 computer, a opaque rectangle appers instead of toolber.
>This area is not updated by VFP 9 application. If I switch to other and them back to VFP 9 application, this area contains part of other application screen. If I move VFP form to this area, the part of form becomes invisible just like in usual vfp toolbar.
>
>Unfortunately this area is not updated and it doesnt accept mouse clicks.
>
>Same application created with VFP 8 SP1 works OK.
>Also, If I run this application from VFP 9 ide, toolbar is also OK.
>