I have Fedora 12 on a Dell inspiron 300m laptop. After I close the lid and open it back the screen stays dark / does not re-activate (sometimes a cursor is present) and the keyboard is unresponsive. The only way to get out of this state is to turn the laptop off through the power button. I tried to play with the acpi options and read the acpi howto. Suspend and hibernate work properly.
I tried to add an acpi handler to the button/lid* event which suspends the laptop, but it didn't work.

Presence of a CRT

It is interesting that the same unresponsive state is obtained when I press the CRT/LCD key. When a CRT / external monitor is present however, everything works properly. Both screens are active simultaneously. Pressing the CRT/LCD button re-activates both. Closing the lid leads to the action specified in the acpi/power configuration, e.g. suspend, hibernate or blank screen. After opening the lid, both the LCD and the CRT reactivate properly.

Does anyone know the solution to this problem?

Suspend / hibernate is often tricky in Linux. You could look at TuxOnIce (www.tuxonice.net).

My suspicion is that the problem is unrelated to suspend / hibernate, because the laptop is unresponsive even if the acpi setting is just to blank the screen. On the other hand suspend / hibernate works fine when a CRT is present. More likely some kernel module or script wrongly expects a CRT / external monitor to be present.

Correction: suspend / hibernate always work, but opening the lid or pressing the CRT/LCD button works only when a CRT is present, otherwise the machine hangs.
By the way, if I manually suspend the laptop and close the lid, when I open it, everything works fine. This is what I have to do for now.