Hi
What's third shift ? A third software ?
If so, the better way is that consult to the product official site about detail information.
Third Shift is the work schedule. I have the same problem. My shift starts at 7:00pm and ends at 5:00am. Outlook will not let me use those start and end values in Options --> Calendar --> Work Time. I found a similar issue on this link: http://answers.microsoft.com/en-us/office/forum/officeversion_other-outlook/calendar-for-third-shift/de24b584-9e37-4af3-9e4c-ef4359fe8065
It appears you've found a design limitation in Outlook. I've confirmed that OWA behaves the same. I'll raise this issue the best I can for what it's worth.
In addition, I recommend that you post this in the Outlook Forum: http://social.technet.microsoft.com/Forums/en-US/outlook/threads