Bug links or load on a site

Hi,

we have a sharepoint 2010 install with 2 sites collections. Each were created since 2 years. Everything work greats until now, but, since a week, we have trouble on one site collection.

When we connect to it, we can see the first page with a webpart about a documents list. When we want to access on a document or a folder of this list, the first time, it's working. But when we want access to another file, the current page was reloaded.

When we are in this case, every link on the site do the same problem. Also when we try to edit the page. Only the site menu work.

If we wait a few minutes (like 5 minutes) on the page, everything work again.

We don't find anything on the log of sharepoint.

Could you help us ?

Thanks in advance !