I am having a hang issue with my R400 with Windows Vista 32-bit. I close the lid or after it's power mode causes it sleep, and it goes into sleep. when I open the lid again or move the mouse around, the little icon shows it's not sleeping anymore, but the screen does not turn back on. Pressing any key (including the FN key), moving a mouse, or closing and reopening it will not make the screen turn on. The only way is to hold down the power button until it shuts off, and then turn it on again. Which of course Vista reports as the previous system shutdown was unexpected. I'm also getting an event log message saying it didn't properly go to sleep. For now I set it to never go to sleep and keep the lid open at all times. Any suggestions?

For some reason your issue is oddly familiar and I think it was down to an issue with the battery or the BIOS - I've done a couple of quick searches on the usual forums but I honestly can't find the blasted thread that had it listed.

this is what I found when searching.
viewtopic.php?f=2&t=76954