I installed xfce4-timer. Version 0.6. When add, for example: 6 hours, 5 minutes, 3 seconds. Everything's OK. But when you add: 0 hours, 5 minutes, 3 seconds. Added 5 hours, 3 seconds. So I did not find component timer.
I couldn't reproduce the problem with timer 0.6.1. Are you sure you didn't enter the wrong fields? Can you test with 0.6.1? If the problem still exists, I think you'll have to provide more information about your installation and packages.
I have this bug with Xfce 4.8 and timer-plugin 0.6.1. If I enter a preset with 0 hours, x minutes and y seconds, the description text says "x h y s" instead, but the time period is still measured correctly. I followed it to the po/ru.po file in the source (I use the Russian locale, and the bug reporter, it seems, too). It has #: ../src/xfcetimer.c:484 ../src/xfcetimer.c:558 #, c-format msgid "%dm %ds" msgstr "%dч %dс" on line 60, while it should be #: ../src/xfcetimer.c:484 ../src/xfcetimer.c:558 #, c-format msgid "%dm %ds" msgstr "%dм %dс"