When did the offending transactions occur?
If recent, I was pondering the same issue today, especially now that the Chinese have overtaken the rest of the world in wallet downloads on Sourceforge. Ever since a documentary on BTC aired a couple of days ago on CCTV, Sourceforge has been slower than usual.
I reformatted my PC today and downloading the blockchain seemed to take longer than usual too.
It wouldn't surprise me if all of this is due to the new Asian burden placed on blockchain, after all, miners subsidize transactions right? And there certainly couldn't have been a dramatic increase in Chinese miners..
My guess is that this will be a transitory problem now that ASICs are hitting the market and difficulty will decrease substantially.
Although we're still waiting for India to join the party...