Thanks for your helpful information.
I has reading a lot about this topic.
I modify my systems to be all forms modeless and I have no more problems with activeX.

About the use of pageframe, I read in MSDN that when you use activex controls in some page, instead turn it invisible when switch to another page, you must call UIEnable(.F.) for each activeX in all inactive pages. This prevent that activeX controls brings to front.

Thanks Again,
And sorry by my english