I created a power pivot model that is connected to about 5 separate spread sheets. I am using 64 bit excel and have 8gb of ram. Recently the I have being getting the attached error message whenever I tried to refresh the pivot or add a measure. If I repeat the refresh it does eventually work. I found one blog post that suggested cleaning out the Vertipaq temporary files but could not find them on my computer. I also downloaded and installed the latest version of Powerpivot.
I appreciate any help.