you did not mention what OS you are using, although it sounds like OS X of some flavor.
You might want to go with an Archive and Install to bring the system back up to par.
If you are using IE, you can dump the temp files in the same way as you would do with windows.
All the symptoms would indicate a corrupt system, which can be fixed
I am a convert from Windows, more out of curiosity, and right now I see no strong compelling reason to switch to Mac full-time. In fact, I prefer the 50-50 concept. I use my Ibook G-3 at work to view my email, and recreation, in addition to using it at church for my power point presentations in Sunday School.
Sometimes my browser, any browser (IE, Safari, Opera, or Mozilla) will freeze up or crash and I would need to force quit the program, especially Safari. I have no idea why. I also notice no indication of temporary internet files on the Mac. Are there any? On Windows, the user needs to dump the guys once in awhile.
Also, on an unrelated issue (?), my QuickTime viewer would also crash while watching a mpeg, etc. BTW, why doesn't QT play wav files?
Are these problems a system problem or a program failure?