Acer Aspire 5742 (2010)
All drivers up to date.
For 18 months my iPhone would charge and access iTunes through any of my 3 USB ports.
Then--in the same week (coincidentally after an iOS update in January) two of my 3 USB ports would no longer recognize the iPhone. Symptoms vary, but initially I got a warning message on the iPhone saying "Charging is not supported with this device"; The computer would flash a message saying "USB device not recognized" or the phone would start charging, the computer would beep and stop the charging--cycle would repeat. Sometimes iTunes will recognize the device and I can download to the phone, sometimes not.
No other USB device (printer and flashdrive)can now use these two ports. However all devices work perfectly on my third USB port.
I have uninstalled and reinstalled the USB drivers, iTunes, checked and updated all other drivers--all to no avail. I fear the day my third USB goes out.
Thanks very much,