Only thing I can say for 100% certain is that I have 5.5 and 6.x loaded on G5 and G6 DL360s and DL380s without issue. The G6 is only supported for up to 5.5 on the HCL VMware Compatibility Guide: System Search .
Can you go in and reset the BIOS to factory and re-enable all of the virtualization items and performance options. You could also try tossing a USB drive inside of there to install to. I do have this 100% functional though with no issues.