It may very well be something simple... power supply maybe or hard drive. Pretty simple fixes.
A year ago I would have recommended Lenovo. I have a 4 core i5 340GHh w/ 8g ram and a 7200rpm hard drive. Not exactly a powerhouse but I don't game so it should be way more than I need. Still seems too slow. Maybe its just getting old or I've developed a tolerance
It's the best machine I've owned so I might still recommend the brand but next time I think I'll build my own.
Hope your problem turns out to be minor.