I'm only human and humans can make mistakes. When making a mistake you should be able to set things right! That is what I want to do in this reply. ;)
At first I thought this Aslain's Modpack caused the troubles of crashing the game, etc. But I found out it didn't!!!
After my earlier post here I uninstalled the Aslain's modpack, uninstalled the game, cleaned my computer (even the register) and reinstalled the game (clean install) with another well known modpack (OMC).
AVG doesn't alert anything for OMC so that was a good start. Everything looked good. But ... I already missed the Aslain's Modpack. It has more potential, more thing on board and it looks more conveniently arranged. :(
I started some battles and suddenly the game crashed. And I was not the only one, so it appeared. When I re-entered the battle (just restarting the game) other people were complaining about game crashes. So I had to try it.
I did it all over again: uninstalling the OMC modpack, uninstalling the game, reinstalling the game (clean install), reinstalling the Aslain's Modpack. Okay ... I have to disable AVG when installing the modpack but it's completely save to do so!!! I hope one day AVG will look at this problem and solve it. :)
Now I have my beloved Modpack again!!! :D So ... to be clear ... Aslain's Modpack doesn't cause any problems with the game or even your computer for that matter. It is a false positive that AVG encounters!!!
I want to apologize to @Aslain for assuming that the Aslain's modpack had anything to do with the occurring problems, 'cause it doesn't. I also want to thank him (and people involved in this project) for doing such a great job!!! :D