Loss of 'Access Content' in Node permissions

Hi folks
not sure if this really is a bug, buy my Durpal install has caused me no end of grief the last few days as I have tried to track down why on my Access Control page, under Node, I have lost 'Access Content' as an option. I tried to look through wherever the page is created in the code, then hit on the idea of turning off installed modules progressively. Sure enough eventually the option reappeared and after some more fine tuning I found that the error - whereby the option completely disappears from the list - occurs only when I turn MicroID's on.

I am using microid.info,v 1.2 2006/12/01 according to the module.info file and Drupal is at 5.1 following upgrade.

Like I say, my knowledge of the hook and module system is not sufficient to say whether this is a bug, but I thought I'd better let you all know.

if you need more info - please drop me a line at s.nisbet@mmu.ac.uk