How many components are there, maybe you hit your limit?
How to look at your limits:
Select File-Reports... then choose the Limits report.
Problem you are experiencing is very hard to diagnose with just messages in this community. The problem can a lot of different thing and without seeing the designs, Netlist, libraries it is tough to pin point the issue.
The best course of action is for you to contact Mentor Support.
After a few hours of deleting the components in the ascii file I found the component that caused the problem . Strange I could load the component into a pcb file in ECO mode but not from an ascii netlist. I loaded the component into a PCB file and then saved it bas to the library and it worked ok.