Options and Attributes won't works correctly

Hi all!

I have installed an opencart 1.5.1.3.
This is my steps:
- createn a product
- create an option group
- create an options with values
- go to the product edit page, and try to assign options to product
There is the first bug: when I tryed to assign third option group, and tryed to add a 4th option-value, the system goes to the login page every time and lost the session. I tryed to create new groups with new options and new product, but the bug randomly follow me:)
Second bug:
- I try to reinstall my shop, but the older 1.5.1.1 version
- options is works fine
- but the "logout bug" found me, when i tryed to assign attributes to the product

What was I doing wrong?
Have you met anybody this bug?

Thanks a lot and sorry for my bad english!

Hi again, I recheck my bug (with the newest version), and when I try to assign 2 attributes to product it works, but when I assigned the third attribute, the system logged out again. Why????

I installed a latest version (1.4.9), it works great, but my new theme is uncompatible with this older version.
Anybody?

And discount also won't works. Can't create a discount for a product