FWIW
This is a peculiar quirk of the lxpanel digital clock which, as far as I know, occurs only
for display formats which don't include seconds. It was well-described in the following bug
report, for which for the complainer promptly reported that it had been corrected:
http://sourceforge.net/tracker/index...58&atid=894869
It has NOT been corrected in the Knoppix 6.7.1 debian choices of lxpanel 0.5.6-1 (stable) NOR
0.5.8-1 (testing). 0.5.8-1 also has other problems, as has been noted by Werner.