When using the Fireball spell, the +50% damage bonus in the spellbook is correctly increased, but in actual combat, it remains normal!
But this is a minor issue! More often, save files get corrupted (especially on the first day!), and when loading them, the game crashes, forcing you to start over!
Here, probably no one plays ERA. Why didn't you mention that you're playing ERA and that the Fireball spell only has issues with Armageddon?
Overall, the report is very uninformative.
What version of ERA? Is it the HD version? What mods are installed and enabled in ERA? Do you experience problems with loading save files on any map?
And does the same happen in ERA without HD? (I'll answer partially for you: in ERA without HD, the Fireball spell behaves exactly the same, i.e., don't ask me about this issue).
Personally, in a clean ERA 2.46 + HD 3.804, I don't experience the save file corruption you mentioned on random and SoD maps.
When HD crashes, it saves an error report in the game folder - HD_CRASH_LOG.TXT. You can send it to me. This may help identify the problem and find a solution.
For questions about ERA, it's best to ask here: http://wforum.heroes35.net/showthread.php?tid=3155&page=1
For questions about HD + ERA, it's still best to ask here: http://forum.df2.ru/index.php?showforum=147
And I check my email. I take all messages into account. But I rarely respond immediately. I may respond in a couple of weeks, or I may not respond at all – I'm busy in real life.