Hi Mr. Exclusive,
If you examine the very first post from me here to you, I recommended trying safe mode, a different account, and using a disk. All three of these things occur before sleep mode is activated. While I can understand if safe mode and a different account still don't work, using the disk should work because it does not access the system to even be aware of sleep mode settings. Sleep mode settings will have nothing whatsoever to do with using the disk. If this problem occurs when using the disk, then the problem is not sleep mode but something else.
In that case, please boot into BIOS (again, this occurs before sleep mode happens) and check the settings there to see if there are any relating to the monitor and its activation or use of sleep mode - if so, make appropriate adjustments to disable sleep mode (but I doubt there's anything there as I've never seen such BIOS settings, but it's worth checking).
You say the monitor says it is going into sleep mode - please provide the exact word-for-word message and how long it stays on the screen.
Please check these things (and of course try them first) and report back.
Thanks and good luck!