I was running into the same problem and error codes as well when trying to use both the iso cluster tool and maximum classification tool.
I first used the "iso cluster" tool to create a signature file in ArcMap 10.. I was getting error codes 010328 and 010267 until I saved the output to my desktop with a really short file name ("iso.gsg"). After I did that, the iso cluster tool worked. I copied it over back onto my google drive filestream directory where I have been doing my other geo-processing and renamed it "isocluster.gsg." The maximum likelihood tool would not run and kept spitting out the same error codes. I finally got it to work by copying the signature file back to my desktop with the name "iso.gsg." I have no idea why that solved the problem... but it worked for me. Might be work saving your signature file to a short name somewhere on your local drive?