The first time I typed 'sync' after untarring the Xfree port.

   The 2nd time (2mins ago) by typing 'vi .cshrc'

   the screen just blanks and starts booting.

Well, that's nice.  How about supplying some more useful information?

* What port?  (I presume i386, based on your previous questions, but I
don't *know* that.)

* What hardware, precisely?  (What CPU, motherboard, disk controller,
disks, how much memory, etc.)

* When was the last time you fsck'd your file systems?