I suspect that the fact that Microsoft have been pushing frequent updates for Windows 10 may at least be a contributing factor. Like many others, I've had no problems with iTunes since upgrading to Windows 10 (indeed, iTunes has been one the least problematic apps - several of the built-in Windows apps, including Mail and Schedule - have been causing more problems).
From reading through other reports here, it is definitely advisable before upgrading to Windows 10, to:
- backup your iTunes library (which should go without saying, as you should backup all data before applying a major OS update)
- deauthorize your Apple ID in iTunes - there seem to be cases where iTunes loses its authorization information during the upgrade, giving some users with reauthorization issues if their count of authorized devices is already maximized at 5.