I installed a new Radeon HD6450 Graphics card on Wednesday. (Meets specifications as best as I can tell). Since then, if I plug anything (external hard drive or memory card reader) into any of my 4 USB ports, LR6 freezes up within seconds. If I try to close LR or click on any another window (Firefox, Photoshop, Task Manager, etc), then the windows start blending together (sorry, don't know how else to say that). Sometimes I can finally get Task Manager into a full window and end LR. Other times, I've just had to turn off my computer with the power button. I tried reinstalling the USB drivers but that didn't help. I also plugged EDs and card reader into my laptop, and they ran fine with LR6 there. I have absolutely no idea what to do. Thanks for any suggestions.