Resharper Build: Seemingly random complete rebuilds

Hello all,

We have a reasonlably large solution (126 projects) and often experience annoyance at the amount of seemingly unnecessary project rebuild VS sometimes performs. So I was very excited to test the Resharper Build functionality in R10.

What I notice now is that Resharper randomly (at least, it seems to me) decides that every single project in our solution needs to be rebuilt. This happens about 40-50% of the time when clicking play, or clicking Build. The other half of the times Resharper correctly marks the unalted projects as 'not necessary to rebuild'. This happens after minor changes in the top projects, the lower projects or even after  not changing anything, just stop-starting the webapplicaiton.

Because the size of our solution and the amount of evolution that it has gone through  in the years I assume there might be something in our solution or project files that might cause this. That or either another VS extension that causes this. I know I currently have Productivity Powertools installed.

My question therefor is: Are there  any known causes that will trigger this bahavior: marks every single project in the solution as 'dirty'?

p.s. I have also noticed that Restarting VS often corrects this bahavior. So after a VS restart Resharper will often correctly see unchanged projects.