CB hung on the "Please wait..." screen (during what I guess is a catalog process) for about 15 mins. Windows then informed me the the exe stopped worked and ask if I wanted to close it.
It's normal that the mount operation takes more time (could take up to 1min/GB which in your case might mean ~2 hours) because backups created with 2.x version don't have an indexation inside, so when mounting a backup, the indexation is built by analyzing the entire file.
But, the program should not crash.
Please try again, and if it crashes please create a dump file. Instructions can be found here
Is there anyway to mount these files?
Once we determine the cause of the crash we can say for certain.
You can also try to restore the backup to a disk/partition which is equal in size or greater than original.