Thanks for your answer,

It is not very easy to reproduce the exception (since as I wrote it appears in unexpected moments). However I am now disposing the Graphics, and also I have rewrite a bit my source code, because i was kind of exploiting this method .

Now I don't get this out of memory error anymore. When I will have some spare time I will look into what You have written Eri.

Thanks for your help and time guys !
Best regards,
Smallbit.