Thanks by your post!

I´ve looked into my log file and no one of my datafile have been skipped, and close and open operations on DB are without errors or warnings.
I´m upset only because this close/open interval is so short, no more than 40 seconds, and i am affraid this cause me some problems in future. By now, I am able to recover my backup with no problems!!
My DB is 3 GB size.
And your suggestions about export, I use this procedure like a alternative way of backup, ´cause, like you, I like to work with EXP/IMP, although is say that exp/imp isn´t a secure way to do backup. Anyway, thanks by it!!
My questions stands: Is normal my close/open time be so short?? Or am i worried without significance?

Thanks in advance!!!!