There are many, many running-related causes of knee pain. Most are related to either overuse or bad biomechanics. But can you provide some more information - location of pain (inside, outside, above or below knee?), when it hurts (uphills? downhills? flat ground? does speed make a difference?), etc - that would help us point you in the right direction.
You might also want to post this instead in the Med Tent forum instead of Newbie Cafe - there are a number of people active in the Med Tent forum who are PTs and really know their stuff.
"...I've learned that you shouldn't compare yourself to the best others can do, but to the best you can do....I've learned that you can keep going long after you think you can't..." --- author unknown
2013 highlights...
@ 5K:
Ontario Mills 5K, Ontario, CA, 24:42
Heart of the City Run, Los Angeles, CA, 24:13
Downtown Anaheim 5K, Anaheim, CA, 24:32
@ 10K:
LA Chinatown Firecracker 10K, Los Angeles, CA, 51:42
The Great Race - Old Agoura 10K, Agoura Hills, CA, 51:12
Fiesta Days Run, La Canada, CA, 49:31
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