I have an LG Flatron L204WS, it has started constantly going into 'analogue power saving mode'

It is impossible to get it to resume the windows session and the PC is now almost unusable, any ideas what could be happening.

The monitor is under warrantee and i dont think it is a graphics problem. I recently have gone back to a small monitor after using my HDTV and since then these problems have started.

Since it is still under warranty, I would contact tech support. Did you install the drivers that came with the monitor?