Hi All,
I just want to share my experience with a recent Plex issue becuase it could be useful for someone experiensing similar issue.
I had been using Plex for a couple of years now and had no issues with it whatsover. I watch it on Roku, my Android device, PC. Share my library with friend and it worked flawesly. I really thik it is GREAT.
However, yesterday for some reason my Plex Server failed to start when I started my machine. When I run PlexMediaServer.exe the icon briefly appier in the tray and disappear as soon as I move mouse over it.
I went though numerouse forum posts trying to find solution. But nothing worked. I did re-insatlled it using latest version from Plex site. I tried reset procedure explained here https://support.plex.tv/hc/en-us/articles/201119258. Nothing worked. The funny thing I didn't see any Crash files or even log files in ..\Plex Media Server\Logs folder. Niether any windows EventLogs. It's like the killed as soon as it's stated.
Finally I figured out the problem.
Previousely I had changed default path for my PMS cache folder, becuase it was getting big (over 3Gb) and I was running out of space on my C: drive, so I move PMS folder to another drive and change setting in Plex to point to drive M:. For some reason (which I still need to find out) my drive M: was re-mapped to different letter and became drive G:. I didn't relized it at the begining that I don't have drive M: anymore. So PMS when started was trying to load profile form drive M: was not able to do so and quit with no message. That is the reason I didn't see any logs or crash reports. The reinstall didn't work because this information is stored in regestry at HKEY_CURRENT_USER\Software\Plex, Inc.\Plex Media Server and is not removed when you uninstall PMS. So when you re-install it is using the previuse profile settings.
The way to fix this issue is either re-map the drive to the old letter or modify LocalAppDataPath variable in "HKEY_CURRENT_USER\Software\Plex, Inc.\Plex Media Server" to a new drive.
Few suggestions to Plex development team in case they read it:
1. Give option to remove regestry setting during uninstall, so next install refresh regestry settings
2. If profile folder can't be loaded on start-up - log error to Windows EvenLog with appropriate message.
Hope this post will help someone.
Plex - RULES. Love the product. Keep up the good work and thank you!!! 
