Will the 'sync' system call cause system crashe

[qhlonline]

Hi, all:
  I have made a test to fill a disk partion with small files and then remove 
some of them to create a large file. The program will run with some operations 
of partion umount, format(mkfs) and mount. This test program didn't always runs 
well, some times it will cause the computer death. Now I think may be the 
crashes happend when my partion was full of small files and then an 'sync' call 
occured, some thing may be need to write back to the partion from memory but 
there are no free disk left, then the system go dead. Is this idea reasonable? 
And is there and other possible reasons?