Help

[hils]

My computer is FUBAR. It's running really slowly and random programmes keep shutting down because of a memory problen. Now, I'm only using about 25% of my hard drive space so it can't be that. It's been suggested it might be spyware/adware. Any idea how I sort this out?

Also, I think I need new anti-virus software. I'm using Norton at the moment but it's shit. Any recommendations? Preferably something not too expensive