Hi, I have a 2007 Macbook 2 GHz Intel Core Duo. Decided to upgrade memory to 2 GB. Followed instructions in manual ensuring memory pushed in fully. After fitting the Macbook wouldn't start up so I refitted the original memory, but still got no response. Thinking I hadn't pushed them fully home, or had bought the wrong type I repeated the proceedure several times, with both old and new memory. Was about to give up when the fan started whirring and it started up without incident, although the green light on power lead wasn't lit and wouldn't recognise battery. Checked memory in profiler and it showed the updated 2 GB. Tried resetting system management controller as many symptoms present but to no avail. At present the power button often doesn't respond to switch on. When it does decide it wants to work the following occurs: The fan is always on. The green power lead light is never lit. The battery is not recognised but will power the Macbook when the power lead is disconnected. Previous to this I had no problems apart from a failed optical drive over a year ago which I didn't replace, I just used an external drive which works fine. Any help and advice much appreciated.