I have reinstalled it again and now it´s okay ! Thanks so much.

Thanks for your reply. Yes I download for the oficial site, but when I made a Google surch, I found that there is a spywhere named dosbox, maybe that was the mistake ... excess of zeal ( I don´t know if this is the right expression in english ). Are there any one with the same problem ?

My Kaspersky Anti-Virus found a riskware Keylogger in the DosBox.exe ! It´s a harmless component of the program or it´s a real spyware ?