weird problem with tab control

hi guys,

i have a weird problem with tab control and i need your help here.

i have two tabs in my control.

1) i set the first tab in design time as the
default tab. as a result, when i switch to the second tab in run time one of the fields in the second tab isn't visiable. this happend randomly,
diffrent field everytime, and sometime it doesn't happend at all.

2) after i gave up fighting this i change the default tab in design time to the second tab.
as a result, the caption of the first tab changes
every time i switch between the tabs.
the caption changes to the names of the fields in the same tab. for example if i have a control name cmdOK then the caption is also cmdOK.
again, this happend randomly and sometimes doesnt happend at all.

p.s. i dont have any line in my code. all the work i did in design time.

when i askd my friend about it he thought i m joking with him. it does sound silly and funny...
but i this is not a joke. just weird!!

pls help
thanks,
ohad.