Theres a wealth of great information here that many will find useful, so we've elected to maintain it in a read-only form.
This part provides solutions for some intractable i Tunes (DRM) video playing/converting/syncing problems as well as i Tunes e Books and photo transfer issues.
I sometimes find the Java setup on my various Apple devices to be a mystery.
Recently, I was trying to get a Java applet to run in the same way on 2 i Macs and my Mac Book Air.
Check answers for how to convert i Tunes M4V to non-DRM MP4 or other formats, how to sync i Tunes movies from PC to Mac, how to add photos from PC to i Phone without data loss, etc. Fixing Apple ID account errors is a crucial first step for using both i Tunes and i Devices, especially for purchasing and file streaming.
Go get the answers of how to delete an Apple account or buying history, unlock Apple ID, reset password, merge i Tunes Store account, etc.