iCal Started Playing Up

[BeeS4335]

For some unaccountable reason my iCal has decided to play-up. If I do a search, for example, it now will not allow me to clear and perform another search straight after. Well, I can clear the search field but when I type in another keyword(s) it won't perform a new search. Also, the Today button doesn't always respond -- if I scroll ahead several months, the Today button remains greyed out. And twice iCal has frozen on me. So, in general, it has started to misbehave and I wondered if anyone had experienced anything similar. Is there a simple way to "repair" iCal? By the way, I've not installed any new software since iCal started to go "buggy" on me. Mine's a MacBook Air running OS X v10.5.4. One other thing: my quick-fix is to quit iCal and restart - the problems go away - BUT they do return!!