If got a serious error with ESX 4.1 build 260247.
When use use on ESX 4.1 build 260247 a VM with Windows 2003 sp2 std x86 4GB Guest Mem with the /3GB switch in the boot.ini.
Memory gets corrupted.
Without the /3GB everthing is OK.
Appendix:
The memory corruption happen only, if I upgrade the vmtools on the affected guest.
VCP4 & VCP3 & CCNA