Gilly

Hi, I'm having problems with my PC and need advice from people who actually know what they're talking about! The PC is a Packard Bell and runs Windows XP Home Edition. When I turn the computer on I hear the fans running, but the monitor remains blank. I've checked the connections and they're fine, and the monitor isn't broken so I know the fault isn't with it. Also the computer will not switch off, no matter how long I hold the power button down for. The only way to switch it off is at the mains. Further info! I was planning to install new anti-virus software on the pc, as it had just expired - pc had not been switched on since it expired, but my first thought was that it could be virus related? On a chat someone suggested it could be a bad motherboard, what do you think? And if so will replacing the motherboard fix the problem? Any advice is appreciated!