This is on a French locale:

 Code:
? "cdbl(1024 / 1000000000) * 48845580: " cdbl(1024 / 1000000000) * 48845580
? "cdbl(1024) / 1000000000 * 48845580: " cdbl(1024) / 1000000000 * 48845580
? "cdbl(0.000001024) * 48845580: " cdbl(0.000001024) * 48845580
? "0,000001024 * 48845580: " 0,000001024 * 48845580


Result:

 Code:
cdbl(1024 / 1000000000) * 48845580: 0
cdbl(1024) / 1000000000 * 48845580: 50,01787392
cdbl(0.000001024) * 48845580: 0
0,000001024 * 48845580: 0
ERROR : unexpected command!
Script: C:\Users\...\test.kix
Line  : 4


Clearly a bug in KiXtart.

Another workaround is to use cdbl() instead of x.0, and don't do calculation in cdbl().