It means you are inserting huge data to your table(s)/database. Change the properties of Database and set the recovery model to simple. If it still doesn't work exec sp_spaceused and post the results to investigate further.
What are you expecting from this post; 48MB is not a big deal and I don't think it is growing exponentially. Log files will not grow with respect to your mdf files, if it is so then there's a problem else this is expected.