While testing a file, I have gotten a recurring class. It happens when pressing the Level Up button after adding a few levels of other classes.... I had 4 levels of Rogue at one point, and 4 Rog, 4 Paladin in the other case. Here is the contents of the error file.
C:\HeroLab\HeroLab.exe
3.4.a 197
ACCESS VIOLATION
Address: 0x004740a2
Type: bad write
C:\HeroLab\HeroLab.exe
3.4.a 197
ACCESS VIOLATION
Address: 0x004740a2
Type: bad write