Opening digital prints from folder with Windows Picture & Fax Viewer?

I'm not sure exactly how to explain this, but I'll do my best. I have a lot of digital pictures in folders on my laptop and I had never had a problem opening them with Windows Picture & Fax Viewer until recently. I had added some new pics from my digital camera a week ago and I always view them when they are done loading. Well this last time I wasn't able to see the pics. I tried several times to open them, but it didn't work. Then my laptop seemed like it was running really slow. I did a disk cleanup and I also did a defrag, which made things run better. I have no viruses on my laptop. Today I tried to open the pics up again to send through an email and everything started messing up again. The digital camera I have is a Aiptek, if that matters any. As I said before, I have never had a problem uploading the pics from the camera to my laptop until recently. I'm wondering if the camera software has anything to do with this problem. I can't remember if there was a CD that I used....