There were several threads on this subject when the 950 first came out. Some people were not able to get their 950 to mount as a drive on both Macs and PCs even though other models of the Sony Readers worked just fine on the same computer. A definitive fix was never found that I've seen posted. When the issue is isolated to the old Sony Reader Library software not recognizing your reader, then a solution is to boot in 32-bit mode. However, it sounds like you have other issues too. You may just have to use your 950 with your wife's PC.
Here is one of the old threads that sounds similar to your problem.
https://www.mobileread.com/forums/sho...d.php?t=130513