I am trying to geotag my archive of aerial photos, and I am doing so by exporting the SD flight log to GPX files and importing them into Adobe Lightroom. Then I notice that all my flight logs from the period June trough August 2012 are off by some arbitrary amount from around 30 minutes to mor than 1 hour 30 min - never the same from each flight log.

I know for a fact that the flight log is incorrect because I have photos of SD on my Ipad showing both time and position. The time matches exactly the time stamp on my camera, but looking at that position on the flight log the time stamp is way off.

Can you confirm that there has been previous errors in the flight log algorithms, or do you have other explanations for these errors?

Also, any suggestions how to resolve?

I'm not aware of any such problems having existed. The algorithm is quite simple; for each breadcrumb we log, we include the amount of time that has elapsed since the start of the log. The time at the start of the log is whatever the current time is, according to your device.