clock.rrd is not being generated from a bbwin client (.12) running in central mode. The client reports clock, but xymon doesn't generate clock.rrd like it does for a linux or unix host.
Clock output from bbwin in central mode:
[clock]
epoch: 1328326750
local: Fri Feb 03 22:39:10 2012
UTC: Sat Feb 04 03:39:10 2012
Clock output linux client
[clock]
epoch: 1328326887.763926
local: 2012-02-03 22:41:27 EST
UTC: 2012-02-04 03:41:27 GMT