32-bit legacy data import filter limitation in 6.4.2. Fix: Break the file into chunks of 300-400 MB, import sequentially, or use the GX script IMPORT_ASCII.gx with memory tuning.
If available, select the version 6.4.2 of Oasis Montaj. Ensure you choose the correct operating system (Windows, etc.). Oasis Montaj 6.4.2 Download