I use Assistant as a user help and documentation system.
When I have modified some files (.qhp in particular), the Assistant crashes when I try to open it from my program.
A workaround is to delete the help directory under ~/.local/share/data/Trolltech/ on the user running the program. This is true for both my own computer and others using our program.
I sit on a Linux system.
I tried googling, but I didn't find any relating issues.
