options changing in products randomly (Memory problem?)

Hey there!

I have an isssue with my 1.5.6.4 installation.
I use vqmod 2.4.1

The issue: I have many options in my shop. When I tried to add a new one. It didn't add it, it disappeared. So I increased the max_input_vars to 7000. I solved this problem.
BUT in some products the options changed without touching them.
For example the size became color, some options changed to another which has nothing to do with the product.
I searched everywhere and I suspect it is caused by the number of options in general. I also suspect it is a vqmod issue.

Does anyone has a clue? cause I have 1500 products and I don't know which have changed .

Thanks members!