Does anyone know if I currently have X2 Producer installed and I'm installing X3 Producer,  is there any reason for me to install Dimension PRO,  the Dimension PRO Expansion Pack, and the three-part package of Loops and One Shots,  or are all of these the exact same thing that came with X2 Producer? 

Skip them, there are no changes to DimPro, the expansion packs or "Loops and One Shots."
Do download the X3e update http://www.cakewalk.com/S...13361/SONAR-X3e-Update
And reset and rescan plugins http://www.cakewalk.com/S...ommended-for-Upgraders

That will save some time.  Thank you! 

Umm ... I'm not liking how X3 installed last night. Along with the Extracting and Installing windows, I kept getting a window saying something like "Sonar is unable to write to the temporary file." I had options to Stop, Try Again, or Continue, I believe they were. I just left that window up, and the extraction and installation appeared to continue. It got to Part4, went through the Melodyne install, and when that was done, it seemed to get hung up with just a small bit more to go on Part4 of the installation. I eventually had to hit Continue on the window indicating a problem, and then it finished, but I'm not sure if everything installed properly. Something like this seems to happen with every Sonar install I do, which is unsettling. Recommendations? Should I try to reinstall it again?
 
Also, the forum would not keep me logged in for some reason last night from my DAW, and so I'm having to post this from my work computer.

I would not trust the installation. May want to check the Windows event log for hardware errors. Make sure the C: drive has enough free space. The installers unpack into TEMP before installing. Sounds like disk issues but could be another system problem.
 
Here are instructions on how to clean and reinstall X3 http://www.cakewalk.com/S...n-Install-Instructions