Various fixes were merged:
- Fixes for 64-bit platforms (Solaris/Alpha)
- Fixes for several engine parameters causing various 
overflows
- Fixes for the Windows GUI and the Linux console progress 
info
- Better error handling (visual messages with the Win 
release)
- Compiling with Visual C++ does not hang the system anymore

Please update to 3.21-5 is you were using previous 3.21 
releases