Magento session and cache makes error in checkout

[supvis]

Hi when I clean cache and remove all sessions i can place an order in magento but when i try it twice or after some minutes, it breaks in checkout, don't save payment method and in cart subtotal is 0.

Also when it occurs is not showing any error but it finish in a server timeout.

Can someone help me? 

Magento 1.9.1

Cache perms: 600

Session perms: 600

I don't know if it is correct.

[Damian Culotta]

Hi @supvis,

Are you sayign that you delete the content of /path/to/magento/var/session ? Why you remove all sessions?

(This is the spanish channel of the forum, so you can write in spanish)