as stated in the rules of this forum "Avoid bumping (reviving) old or new topics; they'll be replied to when they're replied to."
with that said you do not provide any information with your question. no one knows what flash kit you have, what firmware your using, what version of gba exploader your using, what type of msd you have, if you used the panasonic formatter, what rom your running, if the rom is a clean dump, etc.
its no wonder poeple are avoiding offering help.
saving a game puts the save in sram. if you are talking about making an entire dump of sram it may or may not work. this is because the entire sram (which is whats dumped) is not all used for the save data. i recommend you read the readme which comes with gba exploader. there is no way to reply to freezing when no information is provided. all i can add is that gba exploader has never frozen for me on 9 different flash kits.
it is kinda funny because I don't even speak spanish but I joke about this with my friends all the time, it seems like a lot of people in spanish-speaking countries uses the word "buseta" to refer to bus