Dear Graeme, I'm currently testing Argyll with ColorMunki, and found that possibly there is problem in munki_imp.c: line 1339: "data" is being allocated; line 1348: "data" is being freed, however if sensor is saturated, then line 1363: "data" is reused! this leads to GP. I suggest that lines 1348 and 1365 [free_dvector(data,...)] should be removed, and deallocation moved to line 1382 before "if". Yours, Krzysztof Spera PS. Thanks for fantastic job!