Date and Time settings

I can set the date and time on my iMac but when I click on the desktop box to open, it shows the date as Wed 18 Feb 2011 even though it shows the correct date and time on the desktop. As a result my time machine backs everything up as if it is Wed 18 Feb 2011. How do I change this second setting?

Thank you in advance

Do you mean when you click on the top menu date, time and it opens as a small dialog?

If that's what you mean, just click on the bottom item "Date & Time Preferences" and then click on the Date and Time tab. Make sure you click on the small lock at the bottom (password) to open the lock before setting the date and time.

If the date and time are set correctly in the system (as shown in the top menu), applications will use that setting.

Thank you. Yes in the mall dialogue box the top heading shows the date and time as Wed 18 Feb 2011 in grey. In he date and time preference tab it shows the correct date and time, but Time Capsule uses the initial grey setting. If I change the date and ime mnually in the tab section, it does not alter the date and time setting in the dialogue box. In my macbook, both are shown as the same date and time.

Alright, let's do it this way:

Open System Preferences, Date & Time. Now click on the small lock at the bottom and enter your admin password if necessary. Set the correct date and time from the Date & Time tab. Save it. Click on the small lock again to lock it.

The correct date and time should now be set and applications such as Time Machine will use it.

I regret to say that I've tried this already. It doesn't seem to work.
Time machine shows the correct dates as you go back in time but when you put the coursor over those dates, it comes upon every one as Wed 18 Feb 2011 which is also the date shown in the open dialogue box but not on the desktop, which shows the correct date and time.

It sounds like your system is confused. If you have already set in the correct date and time and it's not showing in Time Machine nor from the dialog, it may be time to do a PRAM-NVRAM reset. Follow the instructions given in this LINK.

Again thank you for the assistance. I have reset as per the link twice but it does not help.
I have taken a picture of my desktop showing both dates.

Thanks for the picture. I can certainly see what you mean about the dates being out of sync.

The only other thing that comes to mind is if you have installed any third party apps that enhance the menu or desktop? Applications like "TinkerTools" or any other that might have altered something?

Also check your login startup items in System Preferences, Accounts.