There are enough Samsung users on this forum that I thought it was worth a shot posting this thread... Yesterday or the day before, my wife and I both downloaded the latest Samsung updates to our Galaxy S4 phones. Today, she found that she could not connect her phone as a drive to her laptop, via USB, to transfer files. She had previously been able to do this with no problem. My wife and I bought our S4's at the same time -- they are the same models, have the same Android version (5.01), same Baseband version, etc. We also have the same model laptop. My phone will hook into either my laptop or hers just fine. Her phone will not hook into my laptop either. She called Samsung tech support, and they advised that she load a couple of phone drivers and a USB driver. Those accomplished nothing. FWIW, I don't need any of these supplemental drivers to hook up my phone in drive mode. Any thoughts as to what might be going on with her phone? I tried running the USB debug feature on the S4, but that didn't accomplish anything either. Thanks for any ideas! ETA Never mind...After several hours of maddening debugging, the problem seemed to have been a corrupted micro-SD card. The card appeared to be functioning fine -- it wasn't coming up bad in any diagnostics, and all the files were showing up on File Explorer -- but swapping out for a new card corrected the problem. I couldn't have imagined a more delightful way to spend a Friday evening... .