hydrogen 0.9.4 svn 778 crash changing time from 4/4 to for example 3/4
crash changing time from 4/4 on linux ubuntu 9.04
maybe it will help you and us if you update your hydrogen to svn rev. 1251.
778 is ~ beta2 stage, now we are near rc2 or a release. whatever there are so many alterations since 778 . so it is difficult to say what goes wrong.