Importing does not change the situation. The system crashed almost instantly after executing import. I enabled the debug log, but I am afraid it does not tell anything. I ticked all tick boxes, enabled debugging and tried to import. The log contains only this:
16:51:04: General: Log Reset: Logging reset
16:51:14: Database: MCDB::Save: Start
16:51:14: Database: MCDB::Save: Saving (bCleanDB: 0, bForce: 0)
16:51:14: Database: MCDB::Save: Finish (0 ms)
The system crash happens exactly at the moment when MC tries read the first AAC file. It doesn't matter if the file has been encoded with Nero or iTunes. I have not experienced similar crashes before installing MC 11.1.73 & 74 and trying this. I can import other file types without problems. I am 90% sure the new system is not compatible with the Nero 7 AAC decoder or other included Nero codecs.
However, I am not willing to remove the just updated Nero package. I need it mostly for burning special mode CDs and because of some other utilities included, for example the AAC encoder.
I have not installed any other AAC codecs/filters yet on that PC because it would be good to solve this problem first before adding more factors. Nero is probably the most popular burning utility and it is likely to be installed on many MC users' PCs.
This is easy to try to reproduce. Just clean a PC from other AAC software, install Nero 7 and try.