Windows 7 + DELL G2410 - not interoperable ?

I have  just bought a DELL G2410. It works fine with VISTA.

Given experiences with VISTA I have moved to WINDOWS 7 (Ultimate).

Clean Install (eventually). G2410 connected to Shuttle SX38Pro via DVD-D cable. No additional programs installed, no drivers for ATI 2400 Pro installed. Baseline OS.

At POST no problems......after W7 splash screen goes into SCREEN SAVER MODE and will not ' wake up ' - unable to log on !

Connect old Apple Display.....works like a dream with W7. Is this progress I ask myself ?

DELL Mumbai technical support not very helpful.

Advices please ?

Richard

PS Yes I went into W7 and switched off Display & HD nonsense; they both NEVER switch off. No change in behaviour.