it happens with corrupt images, hh8 finds it hard to read some images also, there are other messages that pop up, like out of memory or out of resources, i have found they all originate from a corrupt or originally poorly imported image in the wil you are looking at.
the only was around is to completely rebuild the wil that your working from, or use someone elses files to see if there wils are corrupt or not.
i had to completely rebuild my hum.wil the other day and it took bloody hours but now no more access violations or annoying messages from hh8.
here is an alternative to hh8
http://www.kaorimir.com/KaoriMIM/
the link lists the features and benefits of the program.