"Random" products disappear when edit order

Hi.

I just finished and opened my 'new' OC 2.0.1.1 for public.
Unfortunately I have a big problem: When I try to edit ORDERs in admin, some products randomly disappears from order!
It shows for a very short moment then it's disappears in a second.

Randomly means here, I could NOT recognize the relation between disappearing products.

Negative and positive stock quantity also disappears and works.
Enabled and disabled products also disappears and works.

Where should I start the debug?
I removed all OCMODS and VQMODS but not solved.

Please help me asap.!! :\

thanks!

... please someone...

Mostly same products appears in edit mode, but sometimes more.
In rare case when I adding a product, it refreshes and all product appears