Yikes!!
ummmm.. Ok I'm Just guessing here..
It's obviously having a problem reading something in memory LOL.. Having never delt with any thing like this and not knowing the specifics of any of what you pasted in It could either be physical mem or the swapping from the page file..
Prorbably the easiest thing to check first would be to swap out the physical mem and see if it crops up again. if it does Then I would consider replacing the HDD... If it resurfaces after that then it may be a Motherboard issue.. Now mind you I am guessing and I am leaning more towards the physical mem being the problem.
Have you noticed any data corruption on the disks.. (problems opeining files, unable to find files that you knew were there, file content garbled etc..)?
does anyone else have a better understanding or another idea?