Certain Programs not opening

Hi,
I did a search for this problem and only found one question with no answers so here goes. I have an iMac 27" running OS-x Snow leopard and it has been working great for almost a year. A couple days ago I noticed that it would take a couple attempts to get Pages to open. But, after doing a forced quit and then a retry, Pages would finally open. Yesterday I could not get pages to open at all. I tried Numbers and it wouldn't load either. But, Safari, Garage Band, Adobe Photoshop, Mail and all other programs all opened fine. I went into Disk Utility and did that "Repair Disk Permission" thing. It did find a lot of errors and fixed them. I tried Pages again and it still would not load. I shut down the machine and restarted it and still, pages didn't load. Finally I did the repair Disk Permission procedure again and when completed, I shut the machine down and restarted it. Now I am able to load Pages and Numbers. Is this a common problem? Can the disk permission issue cause these programs to not load or hang up? If so, how often should one run the repair disk permissions? I have run it three times in 10 months because I read that it was a good thing to do. What can cause all these disk permission errors? I'm just wondering if what I did is a normal fix for this type of issue?

Yes, broken or incorrect permissions can cause applications to not open or fail. And, the best way to repair permissions is to boot your machine from the Snow Leopard DVD, run Disk Utility from the top menu Utilities. Click on the repair permissions button. You can also verify and repair errors on the hard drive the same way.