I have and Acer 4520 laptop which is running just fine till I put it in hybernate or sleep. Some times it can be woke up, but if in sleep or hybernate for long period, then can not wake up. Only way to power up is to remove battery and reseat it...also when I just shut the computer down with it on the charger, the power switch wont work...the only way I can power up is to remove the charger line and power up from battery?? runs fine on charger and battery is charging ok,battery seems ok with aprox 2 hours batt life. wonder if there is ripple or something in powersupply but would think battery would also filter that?
I've seen a lot of this with both Vista and W7 sleep mode. If possible, try disabling sleep mode in the power options and see if that fixes things. Instead of letting it go into sleep mode, just close the lid.