studio 540 usb ports do not recognize phones, camera, iPods or flash drives

Dell Studio 540, 64-bit, Win 7 Home Premium OS (o.e.m.), 500GB HD, CoreQuad processor (2.66 GHz), and 8 GB RAM.

Last weekend, after multiple problems ending in the machine being unable to boot up in any mode, Dell techs directed me via phone support to reinstall the OEM operating system -- which I did. All my files were backed up, that's not a problem. BTW always had Symantec up and running, so no virus issues that I am aware of...

The PROBLEM is that this newly-wiped/reinstalled computer, purchased December 2009, will *not recognize* any USB device except mouse and keyboard and a digital camera. The following devices used to work, just fine -- automatically -- with this machine:

##  three mobile phones - two Samsung Moments & one HTC Hero;

##  four simple iPods - one for each in the family (a 2nd gen shuffle, a 2nd gen nano, two 3rd gen shuffles -- very simple music players); and

##  two thumb drives (flash drives) - both of which are just dumb drives, no extra OS lurking within either of them.

What am I doing wrong? I have re-installed the appropriate folders/files from HTC (phone), Samsung (phone),and Apple (iTunes for the iPods) and directed the Device Manager to look for these devices and to update the drivers for any of them.  No luck.  In most cases, Device Mgr says that the device has *no* driver, and  it doesn't want to load one from the available files nor look for one on the internet -- OR -- it says that, well, I (device mgr) have determined you have the best driver for this device ..., you know, the device I cannot read, locate, operate, or modify, just note that it is there.

Ah, well.

Advice, suggestions -- direction to go?