Can't hurt, I suppose. If that doesn't fix it, you could try getting more info, as follows:
1) Quit System Preferences
2) Open Activity Monitor (in Utilites)
3) In Activity Monitor menu bar, choose Window->Activity Monitor
4) Open Date & Time in System Preferences, and let it "beachball"
5) In Activity Monitor, type "System Preferences" in the filter/search box at the top of the panel.
6) Click on the System Preferences line in the Process Name column to select it, and then click Sample Process. Copy and post here, and perhaps someone can figure out what Date & Time is doing/ trying to do.
Done. Here goes:
Analysis of sampling pid 213 every 10.000000 milliseconds
Call graph:
300 Thread_0f07
300 0xe34d
300 0xe426
300 NSApplicationMain
300 -[NSApplication run]
300 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:]
300 _DPSNextEvent
300 BlockUntilNextEventMatchingListInMode
300 ReceiveNextEventCommon
300 RunCurrentEventLoopInMode
300 CFRunLoopRunInMode
300 CFRunLoopRunSpecific
300 mach_msg_trap
300 mach_msg_trap
300 Thread_1003
300 _pthread_body
300 wait4
300 wait4
Total number in stack (recursive counted multiple, when >=5):
Sort by top of stack, same collapsed (when >= 5):
mach_msg_trap 300
wait4 300
Sample analysis of process 213 written to file /dev/stdout
Sampling process 213 each 10 msecs 300 times
____________________
Tried again and got the following:
Analysis of sampling pid 213 every 10.000000 milliseconds
Call graph:
300 Thread_0f07
300 0xe34d
300 0xe426
300 NSApplicationMain
300 -[NSApplication run]
300 0x7b53
300 -[NSApplication sendEvent:]
300 -[NSWindow sendEvent:]
300 -[NSComboBox mouseDown:]
300 -[NSComboBoxCell trackMouse:inRect

fView:untilMouseUp:]
300 -[NSButtonCell trackMouse:inRect

fView:untilMouseUp:]
300 -[NSCell trackMouse:inRect

fView:untilMouseUp:]
300 -[NSCell _sendActionFrom:]
300 -[NSControl sendAction:to:]
300 -[NSApplication sendAction:to:from:]
300 -[NSComboBoxCell popUp:]
300 -[NSComboBoxCell filterEvents:]
300 0x7b53
300 -[NSApplication sendEvent:]
300 -[NSWindow sendEvent:]
300 -[NSTableView mouseDown:]
300 -[NSTableView _sendAction:to:row:column:]
300 -[NSControl sendAction:to:]
300 -[NSApplication sendAction:to:from:]
300 -[NSComboBoxCell tableViewAction:]
300 -[NSControl sendAction:to:]
300 -[NSApplication sendAction:to:from:]
300 0x15e9e06c
300 _objc_msgForward
300 -[NSObject(NSForwardInvocation) forward::]
300 -[NSConnection sendInvocation:]
300 CFRunLoopRunInMode
300 CFRunLoopRunSpecific
299 mach_msg_trap
299 mach_msg_trap
1 __CFRunLoopDoObservers
1 _CFRelease
1 szone_free
1 szone_free
300 Thread_1003
300 _pthread_body
300 wait4
300 wait4
Total number in stack (recursive counted multiple, when >=5):
Sort by top of stack, same collapsed (when >= 5):
wait4 300
mach_msg_trap 299
Sample analysis of process 213 written to file /dev/stdout
Sampling process 213 each 10 msecs 300 times