There are no browsers open and Software Update does not find the Java 2012 001 update on my iMac mid-2007, although it automatically downloaded it for my iMac mid-2011 yesterday. Both are running the same version of Mac OS X 10.7.3.
Probably a checksum error and may be of no consequence. The update ran successfully on my MBP. It's always wise to do a backup prior to running software updates so that you have a fallback position in the event of a problem.