Welcome to the forums
You've "uninstalled and reinstalled" what, exactly? The chipset drivers? The OS itself?
From experience, I've found that: “Beauty is in the eye of the beer-holder”!!
Smoke Grey Magnesium Alloy Chassis - with White LED Backlights
17" UltraSharp WUXGA Widescreen TFT (1920 x 1200) with TrueLife
Intel Core 2 Duo Processor T9300 @ 2.50GHz (800 MHz FSB, 4MB L2 cache)
4GB (2x 2GB) Patriot Signature PC2-5400 @ 667MHz
DUAL 512MB Nvidia 8800M GTX cards in SLi + 128MB Ageia PhysX
640GB SATA II (2x 320GB WD Scorpio Black 7200rpm)
8x Super-Multi DVD±RW
Creative X-Fi Notebook (ExpressCard) + Creative GigaWorks T40 Series II
Integrated 2MP Webcam
Dell Wireless 355 Bluetooth 2.0 Module
Intel Next-Gen Wireless-N Mini-Card
TV Tuner and Dell Travel Remote Control
4-in-1 Flash Card Reader (SSD/MMC/MS Pro/xD)
230W AC Adapter / 9-cell Lithium-Ion Battery
Windows 7 Home Premium (64bit)
Did you resolve this yet? I've just had this problem and eventually discovered that if I unplugged some of the devices already using USB ports, then new devices would work! E.g. I unplugged my printer and keyboard and then plugged in a digital camera - worked. Same thing for digital photo frame, etc. Must be a power supply issue. That being said....my keyboard has two USB ports in it and when I plugged stuff in there, it also worked! Who knows!