I built my mum a custom pc last year, it worked fine up but had some slight hardware modifications (WLAN card install etc) recently and has slowed down quite a lot, and has gone quite glitchy, I will load a program, flash with another then freeze for a few seconds then boot the program you wanted, should I run some stress tests such as prime95 or something to check for errors? Or anything else that might help? I have defragmented the harddrive already