You might want to open a case with support. I did notice the specific report you are using as an example is one that will return a very large amount of data and depending on how many nodes are in your database, it might very well run out of memory. Try limiting the amount of data returned or running other reports.
Thanks for the reply.
This one which i'm using as an example is the most important for one of our executives. As i said before it stopped working just like that. Other reports are working but much slower than before.
I'll open support case.