my ps2 did the same thing with retail games, i don't know why, but it did just like you said, it took forever to read the disc and for like 90% of disc reading it was not even spinning.
Good to know someone else has seen this problem. Everytime I google search I come up with nothing but DRE problems which this technically is not. Yeah once or twice I seen it report no data. Now when I try googling for solutions it keeps pointing to this thread.....
When my buddy told me about this problem on his console I thought this would be simple fix......Now I feel like less of a man since I haven't been able to fix it.