My WAGuess would be that one of your memory DIMMs is defective and the fault resides at an address which is always occupied by the operating system. GaugePro and its ilk cannot test portions of the RAM which are occupied by the OS.
You can try a couple of things. You could try removing one DIMM at a time and test whether the problem persists. You could also try moving the DIMMs around and retesting. However, keep in mind that you are probably only fully testing the DIMM which is in the middle. That is, the DIMM in slot 2 is fully tested but the ones in 1 and 3 are not.
The reason why I suspect a bad DIMM is the specificity of your failure. It could be that a bad location in RAM is used whenever you activate that particular feature.
You can try a couple of things. You could try removing one DIMM at a time and test whether the problem persists. You could also try moving the DIMMs around and retesting. However, keep in mind that you are probably only fully testing the DIMM which is in the middle. That is, the DIMM in slot 2 is fully tested but the ones in 1 and 3 are not.
The reason why I suspect a bad DIMM is the specificity of your failure. It could be that a bad location in RAM is used whenever you activate that particular feature.