As Tony Nixon has said, the weak pull-ups are too big, you
only need a few k ohms (typically1k - 4k7 depending on the
buss capacitance and speed)

pdf titles 51 to 56 here

http://www.semiconductors.philips.com/products/all_other.html

give you full specs for the I2C bus, and there are many other
pdfs that deal with I2C products

The base page

http://www.semiconductors.philips.com/catalog/

has an index for thousands of datasheets and product /
protocol specs

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